The VW Group could be described as a fundamentalist platform sharer, and no other car shares its floorpan as much as the Golf. The Audi A3 for instance is sired from this platform, and also shares the Golf's solidity, mixing it with a dollop of Audi-cool. Then along came the surprisingly different A3 Sportback - the new tag representing more than just an A3 5-door. We were keen to try it, especially before we drive the BMW 1-series early in 2005. No doubt the Audi diesels will be the stars of the extensive range, though we opted to review the 2.0-litre petrol version, as it shares its direct-injection engine with the Golf we tested earlier in the year.

So what exactly is the A3 Sportback? It does look quite different to the 3-door A3 thanks in no small part to the debut of the new elongated Audi grille and shapely rear lights. The wheelbase is no different to the regular A3, but the overall length has been extended by 83mm. This lends the Sportback a more elegant stance than the 3-door's and, when fitted with the optional aluminium roof bars (£225), has the look of a typically stylish Audi estate, though sportier than the non-RS models. Large alloys play a part in this, and their standard fitment (even the entry level cars have alloys in the UK) indicates that Audi expects style to be a high priority for buyers of the Sportback.

Inside, the A3 Sportback is remarkably minimal in comparison to the equivalent VW Golf. By minimal I don't mean bare, but the interior is much sportier and less fussy. The cabin materials are of very high quality and all controls and surfaces are a joy to utilise and touch. There is plenty of aluminium and chrome, though its use is tasteful. Adding to the ambience of the car pictured is the gorgeous red 'Vienna' leather upholstery - well worth the extra £1,060. Elsewhere, attention to detail shows why buyers might choose an Audi: the trip computer is excellent and easy to use; all electric windows are one-touch and the steering wheel boss is in the same shape as the prominent new grille. The Sportback has a useful helping of extra space in the rear in comparison to the 3-door A3, and without saying as much in its press releases, Audi reckons it beats the BMW 1-series hands down for practicality. The boot is certainly sizeable enough (up 20 litres from the 3-door), though doesn't quite give the A3 enough space to tread on the toes of the much larger A4. Indeed, the unmodified wheelbase has lead to the use of quite short doors, but once inside, passengers have plenty of space.

The driving controls are slick and tactile to use when at a standstill, but we wondered if they would offer the driver the same level of dynamicism promised by the rear-wheel drive 1-series. The pedals are well spaced, and the 6-speed gearbox is wonderfully slick and mechanical in feel. Presumably the transmission is as used in the GT Golf, but the gearchange in the A3 is much more satisfying to use. On the move, the brake pedal was a little too soft for my liking, but full of informative feel. The steering I found to have a curious numbness about the straight-ahead, though otherwise direct and well weighted. The leather 3-spoke wheel is a joy to grasp.

Driven on the limit on twisty B-roads, the A3 Sportback is a more rewarding driver's car than its cousin the Golf GT. Being the Sport version (yes, there is an Audi A3 Sportback Sport!), the car tested has 15mm lower suspension and larger alloys (17-inch) than its standard and SE family members. The A3 Sport is certainly stable on the motorway and not at all harsh. Wind and road noise are well contained. In the dry, the A3 has a surfeit of grip, and the chassis has not been tuned to bring the rear end into play when the driver fancies it. Even in the wet, when we attempted sudden mid-corner lift-off, the rear end stays resolutely planted. This is good news from a safety point of view, but the more committed driver likes to have the ability to adjust a car's attitude. Even using left-foot braking is not an option - at higher speeds it seemed to work, but at more realistic speeds in second and third gear the car's computer decided that an emergency situation was in place and the fuel was cut. In the wet in particular it would be useful to have more adjustment available. In greasy conditions most low profile tyres lose grip before the sidewall has the chance to twist very much, which means the driver has little forewarning.

In contrast to the safe but uninspiring chassis is an excellent traction control system. Most systems we find to be too nannying, and slower responding than a half-decent driver. They often cut power completely when slip is detected on the driving wheels, and take an age to allow power back to the road. The Audi system is a revelation though, maintaining power, while (I assume), applying the brake to the spinning wheel. This works as a pseudo-limited slip differential, and is incredibly effective. The brakes themselves stood up to our less than kind trials without any fade.

The 2.0-litre FSI engine has the same output as the VW Golf GT's, with 150bhp at 6000rpm and a decent peak torque figure of 148lb.ft at 3500rpm. A different exhaust and induction system ensures that the engine sounds sportier in the Sportback, but its power delivery is just as smooth and linear. We managed to average 33mpg in the Sportback, which is a smidgen better than we recorded in the Golf with possibly more motorway miles in the Golf. The difference in weight between the cars is minimal and based on the specification.

For many, the Audi A3 Sportback will be the preferred choice over the equivalent VW Golf (the VW tends to be a little cheaper, but the Audi is well-equipped in return), but the choice between BMW 1-series and A3 Sportback is not so clear-cut. The BMW does promise to be the more involving driver's car, but the majority of drivers do not put that at the top of their list of priorities. Audi's A3 certainly has a more extensive range, which is set to further expand in 2005 with the introduction of V6 and quattro models. We look forward to trying those out for size. In the meantime, the 2.0-litre FSI model is a desirable car to own; it will satisfy most owners all the time, and the Sport model in particular is a competent car; it manages to be sporty as well as comfortable. All being said and done, the "Sport" in Sportback refers to its style as much as to its driving experience.