Test Car Specifications
Model tested: Mercedes-Benz CLS 350 d 4Matic
Pricing: from £57,510 as tested
Engine: 3.0-litre turbocharged straight-six diesel
Transmission: nine-speed automatic, four-wheel drive
Body style: four-door coupe
CO2 emissions: 148g/km (Band 131-150, £200 a year and £450 first year tax)
Combined economy: 50.4mpg
Top speed: 155mph
0-62mph: 5.7 seconds
Power: 286hp at 4,600rpm
Torque: 600Nm at 1,200-3,200rpm
Boot space: 520 litres
What's this?
So, we've spoken elsewhere about how the new Mercedes CLS is, arguably, not quite as good looking as it should be, but for all that it's still a very handsome thing - all hip-high bodywork and smooth styling, and if that interior is not as distinct from the donor E-Class as it really should be given the price differential, then you certainly can't quibble with its quality or functionality.
In fact, perched on very comfortable seats (whose side bolsters actively squeeze inwards as you go around corners) and facing the big, bright, twin 12.3-inch displays for the dials and the infotainment system, it's pretty hard to think of a better automotive interior right now, even if you can get the same effect for less money in an E-Class.
Of course, the CLS is an E-Class under the skin, hence the lanky 2.9-metre wheelbase that means rear seat passengers are far better accommodated than you might expect. Hence the decent 520-litre boot. Hence the incredible list of safety equipment that includes an improved lane-keeping effect in the Distronic active cruise control system, active steering that steps in to help if it detects you swerving away from danger, autonomous emergency brakes, a lane-changing assistant, blind spot monitor and, in Germany at least, a car-to-X communications system that can send and receive warning messages through the traffic management system. Oh, and those squeezing seat bolsters can even nudge you inwards, away from a side impact. Honestly, this thing is very, very safe.
Underneath, our CLS 350 d test car came with the optional air suspension (which can alter the ride height, and which stiffens and relaxes in accordance with the Dynamic Select system that lets you choose from Comfort, Eco, Sport, Sport + and Individual modes. It also had 4Matic four-wheel drive, which will be standard fit on all new CLS models at first, before more affordable rear-wheel-drive versions come online.
The engine is the same 3.0-litre turbocharged straight-six diesel engine as seen in the recently-updated S-Class. It's slowly replacing the older V6 3.0-litre diesel across all of Mercedes' model ranges, and it includes variable valve control and special low-friction coating on the cylinders. Measured on the new WLTP fuel economy test, it returns a decent 50mpg and 148g/km of CO2 in the CLS.
How does it drive?
You now that Bjork song, where she goes 'it's oh so quiet... shhhh... shhhh...'? Well that's what it's like inside the CLS diesel, and there's no sudden shouty bit from a pixie-like Icelandic songstress either. Normally, we talk about the refinement of oil-burning engines with the caveat of 'for a diesel...' Not this one. This inline-six is so quiet at anything other than a pinned throttle that it makes some electric cars seem needlessly noisy and gruff. Six cylinders all in a line is supposed to be the most inherently smooth and refined engine configuration, and Mercedes has clearly made the most of that.
Which is not to suggest that it's slow, either. Peak power of 286hp may sound a touch middle-ground, but 600Nm of torque is more than enough, and with the excellent 9G-Tronic nine-speed automatic gearbox doing the work, the CLS 350 d never feels anything other than sufficiently brisk. You can upgrade to a more powerful 340hp 400 d model, but to be honest we doubt that there's much need to. Do you truly require a big diesel 'coupe' that can accelerate from 0-62mph in less than 5.7 seconds? Thought not...
While it lacks a little of the precision and verve of the more performance-oriented AMG 53 model, this diesel CLS is still good to drive. The air suspension does an excellent job of isolating the bumps, but also keeping the body's motions under firm control in corners, while the 4Matic four-wheel drive made short work of the occasional patches of slippery tarmac we found in the mountains behind Barcelona. The steering has a slight dead-spot just at the straight-ahead position (less so if you're in Sport mode), but it's still accurate and well-weighted. You can happily and enjoyably fling the CLS up and down a mountain pass, but to be honest its metier is really in the outside lane of the motorway, using that torque to despatch slower traffic, and making the most of the refinement and comfort.
I know we're supposed to be giving diesel the swerve these days, but the 350 d engine just reminds you why we fell in love with DERV in the first place. Smoothness, torque, economy and a 600-mile distance to empty readout. If Merc can convince us that this one's not cheating on its emissions exams, then we might start asking to rethink that 2030 internal combustion engine cut-off.
Verdict
Think diesel is dead? the CLS's brilliant 350 d engine proves otherwise. It's actually more refined than the petrol engine in the CLS 450 mild hybrid, has impressive performance and economy and truly exceptional refinement.
As for the rest of the car, the CLS is capable and broadly entertaining to drive, but arguably lacking in the last nth of driver entertainment that you'd get from a BMW or Jaguar. The Mercedes is very comfortable at a cruise though, and almost entirely silent in the cabin, as well as being much more practical than you'd think. Worth the extra cash over an E-Class? Depends on how highly you rate its style...
Exterior Design
Interior Ambience
Passenger Space
Luggage Space
Safety
Comfort
Driving Dynamics
Powertrain
