Driving enjoyment and dynamic handling thanks to technical innovations -- with this message, the new Mercedes-Benz CL marks the new pinnacle of German auto production in this vehicle class. The exclusive character of the Mercedes coupe is stamped by leading-edge technology, including features offered by no other car in the world, complemented by correspondingly innovative design.

The reinterpreted styling of the twin-headlamp front end, the long silhouette and the arched roofline all enhance the dynamic accents of the two-door coupe with typical Mercedes elegance, lending it an exceptional and quite unique appeal.

Deliveries of the CL 500 and CL 600 will start in a few weeks' time from Mercedes-Benz subsidiaries and authorized dealers in Europe and Japan. The US premiere is scheduled for December 1999.

The pioneering top-level technology of the CL make car-driving a totally new experience. Firstly, there is Active Body Control (ABC), an active suspension system that is yet another milestone in dynamic handling and ride comfort.

With high-pressure hydraulics and a high-performance microcomputer, this standard-fitted system adapts the damping of the car body to the current driving situation in a split second. As a result, Active Body Control reduces body movement during drive-off, cornering and braking. The new Mercedes-Benz CL turns corners with greatly reduced body roll, so that when it comes to evasive manoeuvring this system provides much greater safety than automobiles with conventional suspension technology. At the same time, the new Mercedes-Benz flagship coupe with Active Body Control almost matches the high comfort level of the S-Class which comes with AIRmatic pneumatic suspension as standard.

A number of other Mercedes innovations are also going into production for the first time in the new CL, including powerful bi-xenon headlamps for low and high beam, integral seats complete with Easy Entry function for the driver and front passenger, a newly developed multi-link door hinge for comfortable entry and exit and, as an option, an electronic monitoring system for the tire pressures. The technical innovations of the Mercedes-Benz S-Class are also available for the flagship coupe - from the DISTRONIC intelligent autonomous cruise control to active seat ventilation, from the dynamic navigation system DynAPS to the "Keyless Go" chip-card-controlled drive authorisation system.

Finest leather for the instrument panel, centre console, doors and seats
The interior of the CL also fulfils the promise of first-class driving elegance. A harmonious interplay of lines, surfaces, colours and materials forms the basis of the luxury atmosphere, where the tone is set by high-grade wood, fine leather and soft Alcantara (CL 600). The entire instrument panel, seats, doors, side panels and the armrest of the centre console are all covered with leather as standard - and even with extra-soft napa leather in the case of the CL 600. For the wood interior trim, the customer has a choice of walnut or chestnut.

New 12-cylinder engine with automatic cylinder cutout
For the top-of-the-range CL 600, Mercedes-Benz has developed a new 12-cylinder engine with 270 kW/367 hp. Like the V8 engine of the CL 500 (225 kW/306 hp), the 12-cylinder unit is characterised by special technical features such as dual-spark ignition, automatic cylinder cutout and a state-of-the-art modern lightweight construction. The fuel consumption of the CL 600 is 13.4 about 20 per cent more economical on fuel than the outgoing 12-cylinder coupe. Moreover, the new V12 engine already satisfies the strict EU-4 exhaust emission limits that are not due to enter into force until the year 2005.

Body in intelligent hybrid construction
The low fuel consumption of the new CL is also partly due to the technology of its body, which is based on the selective use of different lightweight materials. Aluminium, magnesium, plastic and steel are the main components of an innovative hybrid body construction system that makes the CL a technological standard-bearer in this field as well. For example, the hood, door panelling, rear fenders, roof and other parts are made of aluminium, the front fenders and trunk lid of high-quality plastic and the insides of the doors of magnesium. Systematic lightweight construction in all parts of the body, drivetrain and chassis of the new CL has permitted average weight savings of about 340 kilograms compared to the previous model - despite major improvements in crash safety.

The standard safety features of the CL include: sidebags in the doors, window bags, seat belt tensioners and belt force limiters for all seats and automatic child seat recognition with two-stage airbag activation for the front passenger seat.

More compact body with S-Class level of spaciousness
A new dimensional concept forms the basis for the sporty yet elegant looks of the Mercedes-Benz CL. Compared to the outgoing model, the body of the new coupe is 72 mm shorter, 55 mm narrower and 54 mm lower. The wheelbase has been reduced by 60 mm. The spaciousness of the two-door coupe also satisfies the strictest demands. The interior dimensions for the front passengers - except for 20 millimetres less headroom -- are at the level of the S-Class, and the "hip room" between the front and rear seats has increased to a total of 790 mm. This measurement is an indicator of the passengers' freedom of movement.

Aims: world market share of about 30 per cent
The worldwide demand for exclusive luxury coupes has increased slightly over the last few years, and according to market forecasts will reach a new peak of about 30,000 units in the coming year. The new CL will play a decisive part in this upward trend, with scheduled production and sales of more than 9000 units in its first full year of production.

Superior presence
Coupes are cars of passion. Their appearance arouses the senses. Their message is aimed directly at the heart - attractiveness, aesthetics, charm and temperament. These qualities are matched by formal elegance, technical perfection and exclusivity - especially when the Mercedes three-pointed star emblazons the front end.

The new Mercedes-Benz CL, with its exceptional design, is another example of that very special appeal. It is not only the new flagship model from the automobile marque with the richest tradition in the world, but also the new "dream car" to come out of German production.

With this two-door coupe, all the identifying features of Mercedes-Benz take on a new quality, with optimal safety, maximum comfort, exemplary solidity and - last but not least - undiluted driving pleasure. The CL meets these high demands with leading-edge technology: innovations that no other car in the world can offer give exclusive character to this Mercedes coupe, testifying to the technological leadership of its maker: Active Body Control (ABC), automatic cylinder cutout, DISTRONIC intelligent autonomous cruise control, bi-xenon headlamps and integral seats, to name but a few.

Interior: refined atmosphere with superior materials
Mercedes-Benz has combined these technical innovations with luxury appointments. The interior atmosphere of the CL is distinguished by accessories in leather and high-grade wood from mother nature's rich reserves of finest materials. Fine, high-quality leather is not only used for the seats and parts of the door panels but also for the entire instrument panel, centre console armrest and the rear side panel trim. In the CL 600, extra-soft napa leather is used and is even extended to the rear shelf and centre console side linings. The ceiling and pillars of the flagship model are lined with Alcantara.

Finally, high-grade burl walnut wood confirms the exclusive atmosphere. This material is used for a wide variety of interior details, most strikingly for the centre console and door trim. Instead of walnut wood, Mercedes customers can opt for chestnut wood, entirely as their personal taste dictates.

Engines: choice of eight or twelve cylinders
The new Mercedes coupe will be available as from late 1999 in two variants, namely the eight-cylinder CL 500 with 225 kW/306 hp and a maximum torque of 460 Nm available at 2700 rpm, or the CL 600, powered by a newly developed V12 engine mobilizing 270 kW/367 hp and delivering a torque of 530 Nm at 4100 rpm. Both engines are among the most innovative units of their displacement class. This fact is manifested in particular by the low fuel consumption, which in the CL 600 is about 20 per cent below the values of the outgoing model, and by the exemplary low exhaust emissions.

Dimensional concept: new size for greater dynamism
Compared to the outgoing Mercedes coupe, the new CL is not only more sporty and youthful but also more elegant. Modified body dimensions provide the foundation for looks that are both contemporary and forward-looking. In practical terms, the exterior length of the new coupe measures 4993 mm and is therefore 72 mm shorter than its predecessor. The wheelbase has been reduced by 60 mm and the roof height by 54 mm.

The new CL presents an even sportier image when fitted with the styling package from Mercedes-AMG. The package comprises dynamic-style side skirts and a contoured front air dam and rear apron. The 19-inch AMG alloy wheels in an attractive five-spoke design are particularly eye-catching. They come complete with size 245/40 R 19 tyres at the front and size 275/35 R 19. The mobilo-life long-term warranty -- which Mercedes-Benz was the first car manufacturer to introduce in October of last year -- of course also applies to the new CL. This cost-free service package includes an up to 30-year anti-corrosion and mobility warranty coverage for rust penetration repairs to the body or underbody and ensures continued mobility of the car owner in case of breakdown or car-starting problems. The only condition attached to the lifelong warranty is that the car must be regularly inspected by an authorised Mercedes workshop in conformity with the manufacturer's servicing specifications.

Design: Aesthetics and dynamics in an exclusive package

• Exterior: agility and elegance as design language
• Interior: two-tone leather equipment as standard
• Process: computer-aided design modelling

Design work at Mercedes-Benz means always daring to do something new without cutting yourself off from your roots. This creed was also applied to the CL: although the coupe is at first sight unmistakably a Mercedes-Benz, it also adopts new lines with the aim of high overall aesthetic quality - the perfect interplay of progress and tradition.

The long, flat hood, the stretched roofline, the imposing rear and expressive double headlamps, in a new interpretation of the familiar four-headlamp front end, all emphasize a shape that radiates both sporty temperament and refined elegance. Muscle and unrivalled elegance unquestionably go together here. The visual pleasure inspires a desire to climb in and enjoy the thrill of driving. More particularly, however, the design of the new CL makes the car stand out as unique, both in its broad lines and its minute details.

Long side windows and the absence of B-pillars give a lightweight effect to the basic body. The roofline forms a stretched arch that terminates in the rear pillar, giving the visual impression of plunging deep into the rear. For this effect, the designers have used a styling element that certainly appears new and unusual but at the same time reaches back into the earlier history of the marque: a similarly sporty and elegant C-pillar configuration already characterised the 220 SE coupe that first appeared on the roads in 1961.

For example, the rear lights have been reinterpreted and stylistically refined, but they still create the typical V-look of the rear end. The same blend of reinterpretation and tradition is applied to the headlamps, which are emphasised by the sculpted double tunnels: in combination with the characteristic radiator grille of the SL in the prominent, slightly forward position that has become a family trait, they help give the front end its dynamic appearance.

In other words, the CL is yet another example of the fact that although Mercedes-Benz designers already inhabit the future in their visions, they have in no way forgotten tradition. However, the family traits are not simply inherited but are permanently further refined.

Interior: harmony and high quality
The same applies to the interior, which must of course form a harmonious whole with the outer appearance. The sleek looks of the CL are therefore deliberately echoed in the interior, to sporty, elegant and lean effect. The flowing lines of the instrument panel form a continuous sweep at the joins with the doors and rear compartment. In combination with a two-tone colour scheme for the interior appointments, the result is a very balanced and harmonious impression of space.

The shaping and the materials used evince a maximum of superior value. "Comfortable", "sporty", "refined" and "expertly crafted" are the words that most aptly express the interior of the CL. Valuable wood is dominant in the center console area and in the flowing trim lines of the door and rear compartments - on the CL 600 premium-quality wood is also used around the roof control unit, the rear air vent and the ashtray and cup holder cover in the rear. Leather is also standard for the seat covers, instrument panel, door trim and other interior details and is available in a rich choice of colors - anthracite, Orion gray, quartz and the two beige hues Java and Helios. These dominant colors are also each combined with a darker contrast color.

Process: from computer screen to design model
The new CL largely took shape with the aid of design computers, which for more than ten years have been constantly increasing in importance at Mercedes-Benz. For example, with computer technology the sketches of the design team, which continue to form the basis of styling developing, could be checked for productibility and effectiveness much sooner than with exclusive use of the familiar clay model method. Nevertheless, the first tool remains the pencil. Sketches provided first indications of the possible appearance of the flagship coupe. The inspiration and creative freedom of designers continue now as in the past to define the work in the design studios.

However, the designers very soon transferred their sketches to the computer with the aid of a graphical "digitising tablet". This tool converts the movements of an electronic pen on a special drawing board into computer-readable signals. The designer can thereby draw directly on the screen.

Even though still only two-dimensional, the first sketches of the new CL produced with the aid of special software on high-performance workstations showed whether the design visions could be harmonised with the requirements of the dimensional concept. The dimensional data had already been stored in the computer's electronic memory as a proportional model during an initial phase, so that it now provided a reliable reference for designers. Was the angle of the windshield and A-pillar correct? Was the hood high enough to allow space for the engine underneath?

Even though all specifications were satisfied, the designs produced were very different. However, their effect could only be truly judged by visualising them in space. The necessary third dimension was unfolded by designers as they defined the surfaces of their drafts with the aid of special self-developed programs for car design. The computer did the complex calculations. Hundreds of separate areas are brought together in a few seconds on the screen to form a complete car. As a result, each proposed design can be turned around at will on the screen and examined from every perspective.

Model building

Despite the aid of highly developed computer technology, physical models remain indispensable to designers, because numerous modifications can be implemented and examined more rapidly on a clay model than on screen. For example, less effort is required to correct a hood curvature on a clay model than on computer, where this task is extremely long-winded and cumbersome. On the other hand, for example, different headlamp variants can be tried out more rapidly on the computer.

The use of both methods side by side allows designers to try out more possibilities than ever before. Consequently, almost 20 clay models were produced on the small scale of 1 : 5. Designers finally selected four of these models and had them built in original size. Sensors scanned these large models and transferred the data to the computer. The same procedure was simultaneously carried out for the interior design sketches.

Animation: test drive in virtual reality
However, computers not only make it possible to assess a larger number of design variants and to arrive at better quality models more rapidly, thereby reducing the number of laborious modifications, but they can also provide a foretaste of reality: designers use the data sets to generate animations that enable a car that has not yet been built to be placed in its later environment, in other words to put it on the "virtual road".

Body and safety: An industry first in body development

• Hybrid construction technology: steel, aluminium, magnesium and plastic
• Weight balance: average weight reduction of 340 kg
• Windshield wipers: with aerodynamic wiper blades
• Headlights: xenon system used for the first time for both high and low beam
• Safety: high investment for perfect occupant protection

The body development of new cars is marked by conflicting requirements - on the one hand the customer-oriented goal of exemplary safety and maximum comfort, and on the other the ecologically based demand for lower fuel consumption by means of systematic lightweight construction and good aerodynamics. The new Mercedes-Benz CL is proof that top-quality results can be attained in all development disciplines despite this conflict of aims.

The foundation of this success is a material concept based on four modern lightweight construction materials - aluminum, magnesium, plastic and high-strength steels. Each of these materials is used where it offers the most advantages: steel is used in the zones that are highly stressed in a crash, for example the roof pillars, side members and cross members; aluminum is used for producing parts with a large surface area, such as the hood, roof, rear panel and rear fender; magnesium is used for the inside door panels, and plastic is used for attached parts such as the boot lid, bumpers and front wing.

The result is a new form of hybrid construction that makes the CL a technological standard-bearer in the field of body development. Not only the variety of materials but also the number of joining technologies used is unusual for mass-produced cars. Depending on the pair of materials involved, the body sections of the coupe are flanged, riveted, adhesive-bonded, screw-fastened or welded. Additionally, different processes are combined - always with the aim of achieving top results in terms of structural strength and stiffness.

Doors: magnesium and aluminium combined
In addition to their lightweight construction potential, the new material combinations provide a wide range of other advantages, for example in the production of the doors: Mercedes-Benz is the first automobile manufacturer in the world to use die-cast magnesium for large shaped products (width approx. 1.37 meters) such as the inner shells of the CL doors. Compared to conventional steel inner parts, this method permits the numerous brackets and fixing points for window lift, door lock and other components to be integrated in a single process and with much better formability. Subsequent welding is no longer required.

A special powder coating is used for anti-corrosion protection and at the same time meets the requirements for adhesive bonding between the magnesium inner shell and the aluminium sheet of the outer door cladding. The outer cladding is also flanged to the inner shell. The innovative door construction of the new CL proves that lightweight construction and safety are by no means mutually contradictory: compared to the sheet steel doors of the outgoing model, the use of magnesium and aluminium has resulted in a weight reduction of about 34 per cent with the same functionality and the same strict safety demands.

Door hinges: new technology for comfortable entry and exit
Despite having the typical dimensions for a coupe, the doors provide excellent comfort for climbing in and out of the car. A newly developed multi-link hinge enables the doors to open to a maximum angle of 41 degrees whilst simultaneously moving a few centimetres out from body, so that the driver and front passenger can put their feet comfortably on the ground when getting out of the car.

In the normal space conditions of a car garage, where the gap between the car body and garage wall is usually no more than about 60 centimetres, this ingenious hinge mechanism enables the doors to open to an angle of 23.5 degrees. The front comfort dimension that defines the freedom of movement of the feet in this situation is a good 13 centimetres more than with a conventional door hinge.

Modular construction: easy-to-repair front and rear ends
The CL developers have adopted the advanced modular construction principle already used for the front and rear ends of the new S-Class. These front and rear end modules are preassembled as separate units and then bolted to the body. The individual components of the front-end module are also joined to one another by screw-fastenings. The advantage of this system is that after an accident either the complete module or only the damaged panels of the front end can be simply unscrewed and replaced. The impact energy of less severe front-end crashes, up to a collision speed of about 15 km/h, is absorbed by aluminium crash boxes, so that the side members behind them remain undamaged. Workshop mechanics can again simply unscrew and replace the damaged crash boxes together with the front cross member, which is made from a robust combination of aluminium and steel.

After minor bumps, the broad plastic bumpers at the front and rear of the CL also play their part in reducing the costs of accident repair. They are fitted with special foamed elements that fully absorb the impact energy at collision speeds up to four km/h (rear bumper: up to three km/h). The additional protective strips at the corners of the bumpers and along the full length of the rear bumper trim can be easily replaced after minor bumps without having to dismantle the entire bumper.

Plastic: advantageous for front fenders and trunk lid
These excellent deformation properties are also shared by the plastic front fenders, which are made of a special polyamide blend, a thermoplastic material with exemplary elasticity. After collisions up to 15 km/h, the fenders show no trace of damage. This material also gives the designers of the CL a wider range of possibilities for defining the shape of these parts and, compared to steel, helps trim about two kilos off the car's overall weight.

Another advantage of plastic is revealed in the manufacture of the trunk lid: thanks to this material, the aerials for the phone and automatic navigation system can for the first time be invisibly built into the trunk lid: this type of concealed installation is impossible with conventional steel constructions for technical reasons of reception quality.

Results: progress in lightweight construction and safety
The results of the innovative body construction are there for all to see. The new Mercedes-Benz CL...

• has 58% more torsional stiffness than the outgoing model.
• withstands the toughest crash tests in the world, such as the 64 km/h front-end crash against a deformable barrier with 40% overlap, as required in the "European New Car Assessment Program" (NCAP), or the EU side-impact crash at 50 km/h.
• has a body-in-white about 50 kilograms lighter than the body-in-white of the outgoing top Mercedes coupe, thanks to the hybrid material construction. This weight saving is all the more impressive in view of the additional safety measures (about 39 kilograms extra).

In summary, by systematic lightweight construction in all areas of development, Mercedes engineers have been able to trim up to 340 kilograms from the weight of the predecessor models - despite higher safety and improved comfort.

Aerodynamics: less drag, more safety
For automobile developers, lightweight construction is not an end in itself but a major contribution to reducing fuel consumption, especially in urban and short-distance traffic. In these conditions, a total of about 23 per cent of a car's energy consumption is due to weight-related factors such as mass acceleration and rolling resistance. By contrast, at higher speeds, fuel consumption is dominated by another aspect, which body engineers have dedicated their efforts to improving with the same intensity and success - the aspect of aerodynamics.

With its sportily elegant design, the new CL immediately provides a good basis for low drag. The hood, dipping gently forward, the flat radiator grille, the elongated body, the insets of the rear roof pillars and rear end and the steeply inclined panoramic rear window are all typical stylistic features of the coupe, making the work of aerodynamics engineers easier from the start. Only a few additional details were required to achieve major progress in drag and driving stability.

Examples:

• Small spoilers in front of the rear wheels reduce the Cd value and rear axle lift.
• The all-round lip spoiler built into the trunk lid improves the backwash airflow, thereby further reducing lift.
• The smooth plastic underside panelling, which also fully covers the engine compartment and central floorpan area, channels the underbody wash underneath the coupe with virtually no turbulence.

Another favourable aerodynamic feature is the constant lowering of the body by about ten millimetres up to a speed of about 140 km/h.

Compared to the outgoing model, the aerodynamic drag figure of decisive importance for fuel consumption, as calculated by the product of the front cross-sectional area and the Cd value, has improved by about seven per cent in the new CL to 0.62 square meters.

Progress has been even greater in the figures relevant to driving stability: depending on the engine variant, front axle lift has been reduced by up to 30 per cent compared to the outgoing coupe, and rear axle lift by a massive 60 per cent.

The aerodynamics engineers also paid considerable attention to the safety criterion of "dirt deflection". The rain beating against the windshield and the two exterior mirrors is deflected by special guide channels on the A-pillars and in the mirror housings, so that the view through the side windows and in the mirrors remains essentially clear. The view through the rear window is also undimmed in wet weather, because the water streaming over the car roof is collected in a drain channel in front of the rear window inset and channelled safely down to the sides. The result is that the rear window remains free of dirt up to a speed of at least 160 km/h.

Aero windshield wipers: world debut for a new technology
The CL windshield wiper is also a world first and is making its debut in full-scale production with the launch of the coupe. Here, for the first time, Mercedes-Benz is using "aero" windshield wipers, which provide clear advantages due to their special design. Instead of the articulated U-holder system of conventional wiper blade assemblies, with claws for holding the blade rubber, the aero wiper consists of a single-piece rubber profile with an integral spoiler and external spring rails that are exactly adapted to the curvature of the windscreen. This new wiper blade unit is fixed to the wiper arm by a special adapter that holds the spring rails in position and ensures that the blade assembly is secure. Plastic clips at both ends of the wiper blade provide additional stability. Since the conventional U-system is no longer used, the structural height of the wiper blade is almost halved. This feature is of noticeable benefit in the much reduced wind noise when the windshield wipers are switched on while driving.

However, the decisive advantage is the much improved wiping quality - especially at high speeds on the expressway. The spring rails in the rubber profile ensure that the contact pressure is evenly distributed over the full length of the wiper blade, so that it always operates with the maximum possible contact force.

Light: debut of the double xenon system
Under the project name "Bi-Xenon 70", Mercedes engineers have opened a new chapter in headlight technology, making car driving even safer. "Bi-xenon" means that headlights with gas discharge lamps are now no longer confined only to low beam but are also used for high beam. The entire principle of the headlights is also new: conventional reflectors have been replaced by a projection system that uses optical lenses to concentrate the light and aim it without reflection directly on to the road. The figure "70" in the project name for the headlights of the CL refers to the diameter of the new projector modules.

A single xenon lamp is sufficient for both high and low beam. Whereas in high beam the full light intensity is available, as soon as the system is switched to low beam a shutter moves into position between the lamp and the lens to mask out a portion of the light beam. In both modes, this new headlight system is distinguished by outstanding brightness and long range together with a particularly uniform illumination of the road ahead. The automatic all-round self-leveling of the body by the CL's active suspension system maintains the bi-xenon headlights constantly in the optimal position without dazzling oncoming traffic.

The eye-catching four-headlight front end of the CL permits an intelligent distribution of the different light functions: the bi-xenon systems and turn-signal lights are located behind the plastic diffusion lenses of the outer headlights, whilst the inner headlights comprise high-intensity H7 high-beam spotlights and the parking lamps and side lamps. The front fog lights, with new HB4 bulbs forming a single compact unit with the light fitting, are located in the bumper. Modern microelectronics and data networking of the light system and control units, as already developed by Mercedes-Benz for the S-Class, are again used in the CL to provide new lighting functions that improve both safety and comfort. Three examples:

• Emergency light: In the event of a defect in a control unit or data line, this system prevents failure of the entire front and rear vehicle lighting system.
• Light sensor: In tunnels or garages or in the rain, snow or twilight, the exterior lights of the CL are switched on automatically. A sensor in the windshield takes over this task.
• Delayed shutoff: The front headlamps can be programmed to remain on for a maximum of one minute after closing the doors to help the car occupants find their way in the dark.

Windows: laminated glass with infrared reflection
As in the S-Class, all windows of the CL are also made of laminated glass. For the first time, a new process has enabled Mercedes to manufacture the frameless side windows of the coupe in this safety glass without sacrificing strength but with a clear weight saving of about 38 per cent compared to the previous dual-pane system.

Additionally, the laminated glass construction increases climate comfort: firstly, laminated glass filters the sun's ultraviolet rays with much better efficiency than conventional single-pane safety glass, and secondly, as part of the standard equipment, Mercedes-Benz has lined the window panes of the new CL with metal-coated plastic film that also considerably reduces the penetration of the sun's infrared radiation.

Safety: equal to all requirements
In the field of passive safety, the new CL benefits from the considerable progress achieved by Mercedes engineers in the S-Class. The front and rear end structures of the two models are essentially identical, whereas engineers have developed different concepts for the side panels and the roof. The aim of all these measures was to satisfy the toughest crash tests in the world. To meet the marque's claim of exemplary occupant safety, numerous additional measures have been introduced compared to the outgoing model, resulting in an extra weight of about 39 kilos. Examples:

• Front-end impact: To provide the occupants of the new CL with the best possible protection against the effects of a head-on collision, the stiffness of the occupant cell has been considerably increased by integral reinforcing members in the pedal well, bulkhead and centre tunnel area. The proportion of high-strength and higher-strength steels is also greater than in the outgoing model. Safety innovations already developed for the S-Class, such as the higher-level second side member plane or the ellipsoid bulkhead continue to prove their worth in the CL.
• Side impact: The front sidewall assemblies (A-pillar, inner shell of the side members and reinforcement of the lateral roof frame) are made of high-strength steel. At the rear, depending on the crash stresses, engineers have used aluminium in the form of die-cast parts, extrusions or sheeted panels. The sturdy, higher-strength special steel transverse supports under the rear seats reliably support in the sidewalls in a crash and compensate for the weak point inherent to the coupe design, with its deliberate absence of full-height B-pillars. Cross members also strengthen the body under the windshield, instrument panel and front seats.
• Rear impact: Side members in the form of closed box sections absorb a major proportion of the crash energy in a rear-end collision. The spare wheel, which is located in a glass-fibre-reinforced plastic well, also increases the deformation resistance of the rear end structure, because in the event of rear impact it can rest against the rear suspension subframe. The fuel tank is positioned above the rear axle and is therefore outside the collision zone.
• Rollover: Triple-shell A-pillars made of high-strength steel, together with sturdy C-pillars of die-cast aluminium give the roof structure of the Mercedes coupe the necessary robustness to maintain the survival space if the car overturns. Here again, the CL far surpasses the legal safety requirements.

Restraint system: latest and best technology as standard
The standard restraint system on board the CL contains all the pioneering innovations that Mercedes-Benz has introduced in this field over the last few months. Side window bags to protect the heads of front and rear occupants, full-size airbags for driver and front passenger, two-stage severity-dependent passenger airbag, door-mounted sidebags, retractor seat belts with emergency power tensioners and belt force limiters at both front and back, automatic belt comfort system for the front seats and automatic seat occupancy recognition and child safety seat recognition for the front passenger seat.

Interior: Exclusive atmosphere

• Dimensional concept: S-Class standard of spaciousness for driver and front passenger
• Instrument panel: finest materials and the latest technology
• Seats: new development with integral seat belts

The CL experience begins immediately you get into the car. The driver and front passenger sit comfortably in newly developed integral seats with fine leather covers and will be charmed by an interior design that has been thought through to the finest detail. Everything seems to be of a single piece, in a harmonious interplay of lines and surfaces, colours and materials. High-grade burl walnut or chestnut wood trim adorns many parts of the interior, creating an atmosphere of style and luxury. Fine leather linings embellish the entire instrument panel, armrests and the door and side trim. Soft Alcantara is used for the roof pillars and roof lining of the CL 600.

This atmosphere conveys an unambiguous sense of well being and pleasure. The CL also lives up to this promise with every mile driven. The passengers soon forget they are in a coupe, which normally has more cramped seating conditions than a sedan. Even in terms of spaciousness the CL makes no compromises: the space available to the driver and front passenger is at the luxurious level of the S-Class.

The dimensions for the front shoulder room (1505 mm) and elbowroom (1521 mm) are almost identical in the coupe and sedan. The headroom (936 mm) is only 20 mm less in the CL than in the S-Class and exceeds the headroom of the outgoing Mercedes-Benz flagship coupe by ten millimetres.

The standard-fitted individual seats at the rear also ensure a comfortable ride. Here, the two passengers have elbowroom of 1434 mm, shoulder room of 1387 mm and headroom of 937 mm - values that in some cases far exceed those offered by other coupes in the same vehicle class. In comparing the dimensions of the new CL against the outgoing model, the more compact exterior dimensions of the new model should be taken into account, since they play a decisive part in the sporty yet elegant looks of the new model. Nevertheless, despite a 72 mm shorter body and a 60 mm shorter wheelbase, the distance between the front and rear seats - a key factor in determining the freedom of movement of the occupants - is a full 11 mm longer in the new CL than in its predecessor. Knee room for the rear passengers has also increased slightly, by four millimetres.

Instrument panel: attractive control centre for high-tech systems
In addition to its stylish exclusivity, the instrument panel of the CL provides the same innovative operating and display functions as in the Mercedes-Benz S-Class. These features include in particular:

• The multifunction steering wheel with illuminated pushbuttons for the central display, volume control and car phone. The position of the steering wheel can be adjusted both front/back and up/down with electric servomotors. When the driver gets in or out of the car, the steering wheel is automatically raised to provide more legroom.
• The central display in the instrument cluster, which, depending on the equipment level, displays the functions of the automatic navigation system, tape deck, car radio, CD player, car phone, route-finder and DISTRONIC cruise control. The display can also be used to program individual settings and to display error messages.
• The speedometer with innovative lighting and segmented display when the SPEEDTRONIC speed limiter is activated.
• The COMAND system (standard in the CL 600), with its large colour display in the centre console, that can be used to control the car radio, tape deck, TV set and dynamic navigation system as required. It is also used to operate the car phone and CD changer.
• The automatic climate control with sophisticated sensor monitoring, separate control panels for driver and front passenger and the clear display unit in the middle.

Seats: integral seats for optimal safety and high comfort
Safety and comfort - these two basic Mercedes-Benz features were central to the development of the new integral seats of the CL. "Integral" here means that all components of the seat belt system are directly integrated in the seat, including the retractor with power tensioner and belt force limiter, the automatic belt comfort system, the belt buckle and the upper belt anchorage. This configuration ensures optimal belt guidance in all seat positions, so that the seat belt can always develop its full protective effect. The shoulder belt anchorages for the front seat belts have sliding guides for automatic adjustment to the shoulder height of the driver or front passenger. In this respect, the newly developed seat differs from the integral seat of the Mercedes SL roadster, which has a belt height adjustment system coupled to the height of the head restraint. With their integral three-point seat belts and head restraints, the front seats are key components in the occupant protection system of the new CL. To ensure an effective stop to the forward movement of the occupants in a crash, the seat back and seat frame in particular have to withstand high stresses. A strong foundation is therefore required: Mercedes engineers have developed a special load-bearing structure for both seat squab and seat back: this complex welded framework of aluminum extrusions and formed plates has passed all crash tests with flying colors.

The typical Mercedes comfort of the new integral seat is ensured by a whole range of technical innovations. Firstly, there is the proven innerspring principle, which has optimal vibration properties and has therefore been a characteristic feature of Mercedes cars for many years. Polyurethane foam blocks provide extra support to the inner springs and combine with rubberised hair matting to provide additional damping functions. The pronounced comfort characteristic of the integral seat is emphasised by the soft, high-quality leather cover, with its crinkle effect that already exudes a visual sense of well being.

Extra comfort: lumbar support and multi-contour seat back
To enable the driver and front passenger to make themselves comfortable to their own personal taste, the integral seats not only have electrically powered adjusters for the fore/aft position, height, seat back reclining angle, head restraint as well as squab angle but also have lumbar supports in the seat back. This function is performed in each seat by an individually adjustable air chamber with a pressure regulator located in the lower seat cover. If required, instead of the lumbar support, customers may opt for the dynamic multi-contour seat back that was a world first in the S-Class and already ensures perfect relaxation on many a long journey.

This comfort innovation in the CL consists of a total of eight individually adjustable air chambers - four in the lumbar region, divided into two sets of two, forming the ergonomically ideal bulb shape, two at shoulder level and two in the side bolsters of the seat back. On pressing the "pulse" button on the seat cover, the four lower air pads in the lumbar vertebra region change position by pumping air into the chambers and releasing it again in a precisely programmed sequence. This soft "back massage" effect, which favours the metabolism of the discs and relaxes the back muscles, lasts for five minutes per "pulse" session.

Active seat ventilation, which made its world debut in 1998 in the Mercedes-Benz S-Class, is also available for the integral seats of the CL. Eight small fans draw cool air from the footwell of the coupe and distribute this cooling airstream evenly through the perforations of the seat surface via special plastic ducts and an air-permeable fabric. As a result, the driver and front passenger no longer break into a sweat. Even better, the seat ventilation system also removes existing moisture, thereby drying the shirt or blouse of the occupant. This function provides added comfort even in winter, when seat heating is activated as well as seat ventilation.

Airflow and seat heating can each be regulated by two buttons in the door trim, which also houses the unmistakable, characteristic Mercedes switches for power seat adjustment, as well as the four buttons for the memory function, which can now also save the individually preferred positions of the multi-contour seat back.

Easy Entry: high-comfort entry and exit facility for rear passengers
To help back seat passengers get in and out of the car as comfortably as possible, Mercedes engineers have developed an "Easy Entry" system. Electric servomotors help move the seats and return them to their original position after the rear passengers have climbed in or out. The Easy Entry function, which only operates when the car is stationary with the door open, runs through six phases in a few seconds.

At the rear, the CL passengers are comfortably seated on individual seats. These seats are also equipped with three-point seat belts, belt tensioners and belt force limiters. The folding centre armrest contains the standard first aid box and two cup holders. The stowage box in the centre console between the two rear seats is closed by a wooden roll-top.

As an option, Mercedes-Benz provides a through-load facility with optional plastic ski bag for four pairs of skis. In this case, the fuel tank capacity is reduced by ten litres to 78 litres, and the trunk capacity is also slightly lower.

Electronics: Good connections on three data highways

• Networks: three data bus systems for up to 40 control units
• Keyless Go: chip card for entering the car and starting the engine
• Navigation system: route guidance based on the latest traffic information
• DISTRONIC: extra convenience with intelligent autonomous cruise control

Leading-edge technology of a kind Mercedes-Benz drivers have come to expect is no longer conceivable without the use of microelectronics. The active suspension control of the CL, which is based on split-second interplay between different sensors and actuators, the DISTRONIC cruise control, which automatically keeps the coupe at the set distance from the vehicle ahead (see page 48), or the tire pressure monitoring system are three new examples of the multifarious abilities of car electronics. With the aid of these systems, the Mercedes coupe enters new dimensions of handling safety and ride comfort.

The times are long gone when electronic control units operated alone and only governed their own control loop. The increasingly complex monitoring and control functions of microcomputers demand continuous data transfer between all the processors - in a kind of digital "ring main" that supplies all control units with important sensor data and information.

Three such "data highways" are installed on board the new Mercedes-Benz CL:

• Functions of the engine, transmission and chassis. In this network, data transmission reaches a speed of 500 bits per second (500 Kilobaud).
• One "Class B" data bus is used for data interchange between all the control units in the car interior. Depending on the equipment level of the CL, this bus can connect up to 25 microcomputers controlling about 150 functions and therefore processing about 750 signals - with a transmission rate of 83.3 Kilobaud.
• One "D2B" optical data bus interconnects all audio, communication and navigation systems on board the CL. Fiberoptic cables carry the necessary data through the network in the form of flashes of light at a speed of up to 5.65 Megabaud. With this system, not only control commands but also music, phone conversations or video images can be transmitted by light signal, free of interference and with optimal quality.

The three data networks of the CL are in contact with one another via interfaces, creating a comprehensive information system that covers the entire vehicle.

Keyless Go: chip card instead of keys
The perfect interplay of the electronic components is already evident on entering the new Mercedes-Benz CL - especially if the coupe is equipped with the unique "Keyless Go" system that perfects the security functions of the standard ELCODE access and drive authorisation system. In other words, a chip card takes over the functions of the door and ignition lock. When the owner touches one of the door handles, the chip card receives signals from inductive antennas inside the vehicle and responds by returning a unique radio signal as confirmation. If the codes match up, the doors or trunk lid open. This electronic question-and-answer session between the chip card and the car lasts only a fraction of a second, so that the driver can enter the car practically immediately on touching the door handle - always assuming that he or she has the correct chip card in their pocket.

After getting out of the car, the CL is locked by a similar procedure: the driver briefly presses a button on the door handle, and the electronic device does the rest. A key is no longer necessary to start the engine. A single touch of the starter button on the shift lever of the automatic transmission is enough. First, however, the system runs through an extra data check and only deactivates the electronic immobiliser if this check is positive.

Telematics: dynamic navigation system for the congestion-free route to the destination
Once on the way, electronic systems continue to offer entirely new possibilities to the car driver. The keyword here is "telematics": in conjunction with the COMAND system on board the CL (fitted as standard in the CL 600), Mercedes-Benz in Germany supplies a dynamic navigation system that also takes the latest traffic congestion warnings into account when calculating the best route. This system is based on the technology of the earlier Auto Pilot navigation system, which combines, among other components, navigation computer, satellite positioning, gyro-sensor and a digital road map.

For the new telematics service, Mercedes-Benz has teamed up with Deutsche Telekom in the joint venture Tegaron Telematics, which since July 1997 has been hard at work on system development and establishing the necessary infrastructure. This infrastructure includes sensors on Autobahn bridges to monitor the traffic situation and transmit the latest data by mobile phone to computer control centres. Tegaron then analyses this data in a traffic information database and transmits it on request by mobile phone to the COMAND system in the CL.

The COMAND system is also connected to the Tegaron central computer and sends it data from the car. By this method, individual route selection is possible, taking into account not only the programmed destination and the route desired by the driver but also the latest traffic news relevant to the selected stretches of Autobahn. If a traffic jam starts on one of these sections, the system calculates an alternative congestion-free route within only 30 seconds, to ensure faster arrival at the desired destination. The route guiding instructions appear in the form of easily understood maps on the COMAND system's colour display in the centre console. At the same time, the route guidance symbols can also be shown in the instrument cluster of the central display, which remains constantly in the driver's clear field of view.

The telematic services for German Mercedes customers also include the automatic emergency call system TELE-AID (Telematic Alarm Identification on Demand), which makes use of navigation system components such as the satellite antenna and car phone. TELE-AID automatically alerts the emergency rescue services if an accident occurs and guides them to the accident location.

DISTRONIC: Keeping a safe distance by radar sensor
Another major achievement of microelectronics is the DISTRONIC intelligent autonomous cruise control developed by Mercedes-Benz and available as an option for the CL. This innovative system uses the measurement data from a radar sensor mounted behind the radiator grille to monitor the distance of the coupe from the vehicle in front and correct it if necessary. The distance is corrected either by automatic braking signals or by briefly accelerating the car under the control of the DISTRONIC computer. Practical tests have shown that this innovative system makes a tangible contribution to relieving driver stress. On high-speed roads, DISTRONIC enables the car to "swim with" the traffic flow, whilst constantly checking that the CL is the correct distance from the vehicle ahead.

DISTRONIC is operated by the proven cruise control/SPEEDTRONIC lever on the steering column. With this lever, the driver can set the desired speed between 40 and 160 km/h and activate the distance measuring function. In response, the instrument cluster activates a display showing the desired and actual distance to the vehicle ahead. Normally, DISTRONIC is set to a distance (interval) of 1.5 seconds - which is equivalent, for example, to about 42 meters at 100 km/h. Depending on traffic density and flow, other distances may be recommended, and so the driver is provided with an individual adjustment facility consisting of an infinitely variable rotary control in the centre console.

Chassis:New driving experience

• Active Body Control: new milestone in suspension technology
• Brakes: generously dimensioned disc brakes for optimal safety
• Tyre pressure monitoring: radio signals from the tires

Sporty or comfortable? This key question of suspension tuning is almost as old as the automobile itself, but opinions still differ on the best answer. Should the wheel vibrations caused by the road surface be kept to a minimum by stiff shock absorber settings, thereby ensuring optimal grip between tires and road surface, even at the expense of driving comfort? Or should shock absorption be kept as soft as possible, to the detriment of driving safety and driving dynamics, in order to give the car occupants a smooth ride over uneven roads?

The dilemma does not stop there: the art of the suspension engineer not only consists in finding a reasonable compromise for damping the vibrations of the wheels but also in taking the movements of the car body into account. The imperative need is to restrain the rolling, pitching and bouncing movements of the body whilst maintaining maximum comfort. For that purpose, the car body must not only be sprung as perfectly as possible but must also be effectively damped. The question remains: to what extent?

The Mercedes-Benz marque, which has built its reputation principally on the product characteristics of safety and comfort, has committed considerable attention and resources over the years to solving this technical conflict of aims.

Remarkable success has already been achieved, as is proved by the high safety and comfort level of Mercedes passenger cars. However, the quest for further top performance in this domain is restricted by the narrow limitations of conventional suspension technology.

Consequently, about 20 years ago, the Stuttgart-based engineers started taking new paths and conceiving of an "ideal suspension system" that would perfectly harmonise almost all requirements by means of electronics and hydraulics. The result of this exhaustive R&D work is Active Body Control (ABC), the active suspension system that is entering full-scale production for the first time in the Mercedes CL coupe.

Working range: active control for body vibrations up to five Hertz
In this system, hydraulically adjustable servo cylinders in the suspension struts operate in combination with passive dampers and coil springs, sharing the tasks of suspension control. In practical terms, the actively controllable elements reduce car body vibrations of up to 5 Hz, which are experienced for example as the lifting (bouncing) and rolling movements of the car body on uneven road surfaces, or as severe body roll when cornering, or as the typical pitching of the car body when braking. Depending on the particular driving situation, these vibrations are considerably reduced by Active Body Control compared to conventional steel springs. For the higher frequency vibrations of the wheels (six to 20 Hz), passive gas-pressurised shock absorbers and coil springs are also used in the new Mercedes-Benz CL, but their damping forces are lower than in conventional suspension systems. This configuration has a positive effect on ride comfort and vibration comfort.

Even the stabiliser bars that have long been conventional features of the suspension are no longer needed due to the active anti-roll stabilisation process. The limitation of the active control range to car body vibrations with a maximum of five Hertz is one of the results of many years of research and development by Mercedes-Benz in this domain. A "fully active" suspension system, operating for example in the full frequency range from 0 to 30 Hertz, would require a disproportionately high energy input that would in turn detract from performance and increase gasoline consumption.

Components: teamwork between electronics, hydraulics and mechanics
The operating principle of Active Body Control is based on perfect interplay between mechanical, hydraulic and electronic components.

The main functional components of active suspension are the hydraulically adjusted servo cylinders, or "plungers" in the suspension struts. These plungers essentially consist of a sliding sleeve with the coil spring mounted at its top end. When the car is on the move, the hydraulic system drives the plunger, exerting auxiliary forces that modify the action of the coil spring. In response to any tendency of the car body to pitch, roll or lift, the cylinder generates different degrees of extension at the foot of the coil spring to counteract and significantly reduce body movements.

The amount of pressure applied to the springs and the duration of application are determined by the sensor signals indicating the current body position relative to correct levelling and the body acceleration. This data is processed by the two microcomputers of the active suspension system using special plunger control algorithms.

Whereas, in conventional vehicles, the body movements due to the action of forces of inertia, braking or acceleration and to the variations in wheel loads can only be limited after the event, Active Body Control detects these movements in the very early stages and can immediately correct them, within a fraction of a second.

Road safety: body movements greatly reduced
As a result, driving is transformed into a new experience with Active Body Control. Driving safety, ride comfort and driving dynamics attain even higher quality, as is shown by comparison with the outgoing steel-sprung CL model and with the S-Class, which already reaches a very high standard in these disciplines with its electronically controlled AIRmatic pneumatic suspension.

When cornering or swerving at high speed to avoid an obstacle on the road, Active Body Control has considerable advantages compared to a conventional suspension system, because it first reduces any incipient body roll to a minimum and then stabilises the body in a fraction of a second. This fact is shown by the measurement results of the slalom test, which is used by suspension engineers to simulate sudden swerving manoeuvres and to evaluate the stability of the car.

In "Comfort" mode, the roll angles of the new CL with Active Body Control are as much as 32 per cent less than equivalent values for the steel-sprung CL predecessor model and about 30 per cent below the measurement results of the air-sprung S-Class.

The safety advantage can also be seen in the stabilization time, which in combination with the overshoot amplitude is a measure of the damping of body movement about the vertical axis: with Active Body Control, only 0.4 seconds elapse after a sudden swerving maneuver before the body is again fully stabilized and the danger of skidding is eliminated. In the outgoing model with conventional steel springs, the car body continues rocking considerably longer - for up to 0.6 seconds.

The new CL performs similarly well in the steady-state cornering test, which provides an assessment of how well the car tackles a long bend. Here too, the new active suspension system proves its strengths. It reduces body roll compared to the outgoing steel-sprung Mercedes coupe by up to 68 per cent.

Selection program: individual suspension setting at the touch of a button
Sporty or comfortable? This traditional conflict of aims in suspension tuning is solved entirely to the driver's own taste by push-button in the new Mercedes-Benz CL. Depending on individual requirements or the road ahead, the driver can select between a sporty and a comfort-oriented mode that tangibly modifies the operation of the Active Body Control. As a result, the new CL offers either the dynamic driving qualities of a sports car or the more comfortable handling of a sedan.

In the "Sport" setting, the action of the active hydraulic cylinders (plungers) is increased, so that the suspension characteristic of a sports car is obtained. The advantage of this harder characteristic is evidenced for example in the even lower body roll angles. In "Sport" mode, the roll angles are up to 27 per cent lower than the equivalent values in "Comfort" mode.

Steering: more direct response in "Sport" mode
The stronger reduction of dynamic roll angles in "Sport" mode also affects the front wheel toe angles, with tangible effects in more direct steering response. Mercedes engineers have utilised this effect to increase the agility of the coupe even further. For example, the more direct steering characteristic provides an even higher degree of driving dynamics and driving pleasure, especially on winding country lanes or mountain roads.

However, even in this respect, the system remains active at all times, so that it automatically adapts the steering setting in "Sport" mode to the relevant driving situation and speed. Between 60 and 140 km/h, steering response is at its most direct, whilst at faster speeds the sporty setting is continuously modified. As a result, the driver on an expressway or German "autobahn" will have no trouble keeping the coupe safely in line. Speed-dependent adjustment of the rolling moment distribution, which progressively moves towards "understeer" at high speeds, supports the exemplary straight-running properties.

Ride comfort: reaching the high standard of the S-Class
With active suspension, the new Mercedes coupe also surpasses its steel-sprung predecessor in the domain of ride comfort, where it almost even attains the high comfort standard of the S-Class, which is standard-fitted with the electronically controlled AIRmatic pneumatic suspension. In the test drive on a country lane with a bumpy road surface, the vertical body movements (lifting) of the new CL with Active Body Control are much more effectively damped than in the outgoing flagship coupe with steel springs. The same also applies to the pitch and roll movements provoked by the irregularities in the road.

The vertical accelerations measured in this test for the range above five Hertz provide a recognised measure of a car's ride comfort. In the new CL with Active Body Control set to "Comfort" mode, the results are some 11 percentage points below those of the outgoing Mercedes coupe with steel springs. The CL has therefore clearly entered the comfort dimensions of the S-Class.

*In the frequency range above five Hertz
This result is even clearer when the vertical body movements are measured over the complete frequency range (up to 30 Hertz). This comfort measurement takes into account all influencing factors in a drive over a poor-quality country lane. The new Mercedes-Benz CL with Active Body Control (ABC) - like the air-sprung S-Class - comes out of this test a full ten per cent better than the outgoing coupe.

Self-levelling: automatic lowering on high-speed roads
The performance spectrum of Active Body Control also includes automatic all-round self-levelling based on the actual load conditions. Additionally, the driver can manually vary the ground clearance of the coupe. A push-button in the centre console gives the driver a choice of two levels at low speeds. In position 1, the body is raised from the normal level by about 25 millimetres, and in position 2 by as much as about 50 millimetres. With increasing speed, the body sinks continuously back down to normal level. Then, from normal level, at high speeds of up to 140 km/h, the CL is lowered by a further ten millimetres, thereby reducing both air resistance and fuel consumption.

Chassis: suspension, steering and control systems modelled on the S-Class
For the use of Active Body Control, Mercedes engineers have only slightly modified the newly developed four-link front suspension and the proven multi-link independent rear suspension. The main change is the absence of stabiliser bars, since their functions are now performed by the active suspension system. The other technical features of the CL's suspension correspond to the high standard of the S-Class. In other words:

• The four-link front suspension, which is characterised by precise wheel location, is fixed to a low-mounted aluminium frame-type integral support, together with the steering gear and engine mounts. The tension struts and upper wishbones of the front suspension are also made of aluminium.
• Instead of the recirculating ball steering of the outgoing model, the new CL has been given the rack and pinion steering of the S-Class, since this system has clear weight advantages for the same precision. The speed-dependent variable ratio function is standard.
• The multi-link independent rear suspension has been further optimised in ride comfort and vibration damping. The rear axle support is made of aluminium and is about 45 per cent lighter than the previous component made of sheet steel.
• The Electronic Stability Program, ESP, which considerably reduces the danger of skidding when cornering or in critical situations, is included as standard for the CL.

Brake callipers: new composite construction of steel and aluminium
The brakes of the new flagship coupe are essentially based on the same technology as those of the S-Class. For example, the diameter of the perforated and ventilated discs of the front brakes is 330 mm in the V8 model and a massive 345 mm in the 12-cylinder version. As a result, the braking performance of the Mercedes coupe sets new standards for its class.

Another special technical feature is the composite construction of the four-piston fixed calliper disc brakes for the front wheels of the CL. This new combination of high-grade casting and cast aluminium reduces the weight of the brake callipers by 36 per cent. The two-piston fixed calliper disc brakes for the rear wheels are made of aluminium. 17-inch wheels and tyres are fitted as standard to both CL variants. With a tyre size of 225/55 R 17, the CL 500 has cast aluminium wheels, whilst the CL 600 has forged aluminium wheels - in both cases in size 7.5 x 17. Hollow spoked aluminium wheels measuring 8 x 18, in combination with 245/45 R 18 tires are available as an option.

Tyre pressure monitor: radio transmitters on every tyre
In future, as an option, an electronic system will monitor the tire pressures of the CL. The sensors of this system are installed in the tyre valves and measure both the air pressure and air temperature inside the tyre. Since cable connections to the wheels are not possible, engineers have developed a wireless transmission system that operates in the 433 MHz radio frequency range. Each electronic wheel monitor is equipped with a transmitter that broadcasts the measured data approximately once a minute.

Special antennas in the coupe's wheel housings receive the radio messages and forward them by cable to a microcomputer. The control unit in the front passenger footwell identifies the signals from each of the four wheel-mounted electronic systems on the basis of their individual identifier and can therefore inform the driver precisely of the tyre pressure in each of the four tyres.

Drivetrain:Advanced power plants

• 12-cylinder engine: new range-topping engine with cylinder cutout
• Fuel consumption: CL 600 roughly 20 per cent more economical
• Exhaust emissions: V12 engine satisfies EU-4 standard

More compact, more lightweight, more economical and more environment- friendly - the main differences of the new Mercedes-Benz CL engines compared to the engines of the outgoing model are simple to summarise. In other words, progress all down the line. Two engines are available:

• The CL 500 is powered by the 225 kW/306 hp V8 engine with a displacement volume of five litres, also available in the same version for the S-Class. This 5.0-liter engine develops its maximum torque of 460 Newton-meters at between 2700 and 4200 rpm. As an option, Mercedes-Benz can equip the eight-cylinder unit with an automatic cylinder cutout system that reduces fuel consumption in part-throttle.
• In the CL 600, Mercedes-Benz is using a new 12-cylinder engine for the first time: this unit develops 270 kW/367 hp from a displacement volume of 5789 cc. The V12 engine reaches its maximum torque of 530 Newton meters at 4250 rpm. An automatic cylinder cutout system is provided as standard for this engine.

Three valves per cylinder, twin-spark ignition, lightweight construction and low-friction cylinder liners are the common features of the two CL engines: thanks to these innovations, the engines have up to 20 per cent lower fuel consumption than the engines of the outgoing model, and they also comply with the strictest exhaust emission regulations in the world. The performance data of the new CL are also better than the figures for the outgoing coupe - despite being up to 20 kW/20 hp less powerful (CL 600). The advantages of intelligent lightweight construction and good aerodynamics make their presence felt.

12-cylinder engine: finest lightweight construction
The lightweight construction principle in the development of Mercedes cars also takes effect in the realm of engine construction, as is proved by the new V12 engine: its weight has been trimmed to 220 kg, a reduction of about 22 per cent compared to the previous 12-cylinder engine. The use of highly advanced construction methods and careful choice of materials has made this weight saving possible: for example, the crankcase is made of aluminium, the intake pipe of magnesium and the exhaust manifold of laser-welded high-pressure formed sheet steel. Cylinder liners made of an aluminum/silicon alloy and forged connecting rods manufactured by the crack process provide further weight savings of up to 46 per cent compared to the equivalent technical features of the previous 12-cylinder engine. Last but not least, the three-valves-per-cylinder configuration also helps shed weight, even though the main advantages of this arrangement are in the domains of fuel consumption and exhaust emissions.

With its 220 kilos, the new 12-cylinder engine from Mercedes-Benz is only slightly heavier than the V8 engine, and with its cylinder spacing of 90 millimeters it is also as compact in construction as the eight-cylinder unit. Its cylinder angle is 60 degrees, and its bore/stroke ratio is 84.0 x 87.0 millimetres.

Cylinder head: twin-spark ignition with ionic current diagnosis Each cylinder bank has a camshaft that controls the valve timing via low-friction roller-type cam followers. A microcomputer-controlled adjusting mechanism adapts the control timing of the camshafts to the relevant engine characteristic map, thereby favouring harmonious torque development, which is also assisted by the complex computed geometry of the innovative ram pipe.

The decision to dispense with the second exhaust valve is especially intended to reduce heat loss in the exhaust, thereby improving the light-off characteristics of the catalytic converters after a cold start. This configuration also leaves space for the installation of two spark plugs per combustion chamber. The V12 engine is controlled by an innovative alternating current ignition system and also has a modern ionic current diagnosis system that is making its world debut in this engine. This system detects and corrects misfiring in a fraction of a second - with the particular aim of protecting the catalytic converters.

Cylinder cutout: fuel savings in part-throttle
The standard-fitted automatic cylinder cutout system in the V12 engine deactivates the valve gear and fuel injection of an entire cylinder bank if only a portion of the maximum power or maximum torque is required. This system compensates for the inherent drawbacks of large engines, such as incomplete cylinder charge, low cylinder pressure and high friction, which would otherwise reduce efficiency and result in higher fuel consumption.

However, despite automatic cylinder cutout, Mercedes customers are not obliged to do without the majestic power reserves and superior smooth running of the 12-cylinder unit. The driver simply has to step on the gas, and the deactivated combustion chambers are immediately switched back into action, so that the engine can develop its full torque. The occupants of the new CL remain blissfully unaware of the cylinder bank cutout and reactivation, because any sudden jolting change in torque is prevented in a split second by the engine management computer, by briefly adjusting the throttle valve position and the ignition timing.

The smooth running and noise comfort of the V12 engine also remain undiminished with a deactivated cylinder bank, due to the unchanged balancing of masses in the engine. Higher pressure waves in the exhaust system, which might otherwise become audible, are prevented by a butterfly valve in the venturi tube downstream of the underfloor converters. This valve closes when the system is provisionally switched from twelve to six cylinders.

The technical arrangement of the automatic cylinder cutout system corresponds to the principle of the V8 engine: a hydraulic system isolates the valves and camshaft by separating and locking the levers of the valve gear. At the same time, the fuel supply and ignition are stopped for the left-hand cylinder bank.

Exhaust emissions: below future limits
The other special technical features of the new V12 engine include the exhaust system: a total of six catalytic converters - four bulkhead converters and two underbody converters - together with eight lambda probes ensure that exhaust pollutants are reliably rendered harmless.

Two bulkhead converters are assigned to each cylinder bank. Thanks to the low heat loss in the exhaust system - a result of the three-valve configuration and the air gap insulated exhaust manifold - the bulkhead converters reach their operating temperature within a few seconds after the engine is cold-started. Lambda probes monitor the exhaust gas composition upstream and downstream of the bulkhead converters. The data from these probes is analysed not only by the engine control unit but also by a special on-board diagnostic system.

As a result of the perfect interplay of modern engine technology and effective emission control, the new CL 600 already complies with the emission regulations of the future: the exhaust emissions of the 12-cylinder engine are below the limits of EU-4, which is not scheduled to become law until the year 2005.

For reasons of noise and vibration comfort, the exhaust system of the CL 600 is designed as a double-flow system. Upstream and downstream of the underbody converters, the two lines are brought together for a short mixing section. The downstream section contains the valve that automatically closes to prevent uncomfortable pressure waves when the left cylinder bank is deactivated.

In this case, only a precisely calculated gap still remains open for the exhaust flow. Downstream of this mixing section, the exhaust system again branches into two lines, before finally ending on both sides in chromed, oval-shaped tailpipes.

Automatic transmission: extra comfort with one-touch gearshift
The proven five-speed automatic transmission with electronic control, two shift programs and torque converter lockup clutch is fitted as standard in both CL models. The newly developed one-touch gearshift that Mercedes-Benz introduced for the first time in the S-Class is again used here to provide maximum operating comfort: in the "D" position, a single light touch of the shift lever to the left or right is sufficient to shift manually between 1st and 4th gears. A display in the instrument cluster informs the driver which shift program is currently activated.

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