Audi A6

the new A6 is a big improvement over the previous car and now offers class-leading levels of space, build and engine refinement. The looks will grow on you, and it has become a genuine large executive contender. But the chassis and steering could be weak points against Audi's key German rivals. We'll have to wait for it to arrive here for the definitive verdict.

It seems that Audi isn't happy to let BMW court all the hype and controversy. The Bavarian company's styling has attracted a fair share of comment recently, so the design department at Ingolstadt is getting in on the act by renosing Audi's models with a contentious family grille.

The latest to get this treatment is the all-new A6, the previous version of which won praise for its understated styling. It's fair to say that the new look hasn't been universally well received, but we would urge people to wait until they see it in the flesh. It's certainly a very muscular car, helped in this respect by the short overhangs front and rear and the bluff face. But Audi has managed to retain the clean lines that marked out its previous models, and there's more than a hint of A8 about the rear. It's finished off with a small 'kick' in the top of the boot, to aid stability.

This is good news, because the new A6 certainly doesn't hang about. Even the diesel we drove delivers a claimed 0-62mph time of 7.3 seconds, which is marginally quicker than both its main rivals, the BMW 530d and Mercedes E320 CDI. However, it's more a question of the pace creeping up on you rather than any real shove in the back.

The powerplant is quite subtle, mainly because it's incredibly refined at high speed - in fact, it rarely sounds like a diesel, and there's a fantastic rorty edge to its exhaust note. It also does a pretty good job of containing any of the vibration that is normally associated with oil-burners. Other emissions are less welcome - 223g/km of CO2 is high compared to its rivals, although the unit is compatible with Euro IV emissions rules to lower company car tax bills. The A6's refinement is also helped by the seamless changes in the six-speed tiptronic transmission - although this is also the weakest part of the powertrain, because if you plant your foot, the revs zip round to the red line and stay there. It feels similar to driving a vehicle with Continuously Variable Transmission - which is another option available, along with a new six-speed manual gearbox.

The chassis is refined as well, and copes admirably with bumps around town. However, we'll reserve judgement on the high-speed ride over more broken surfaces until we have driven the A6 on some of the UK's poorer-quality roads. It feels stiff, so it doesn't float at all over longer undulations.

One advantage of this is that the Audi has little body roll in corners, but the steering lets the car down because it gets quite vague at the dead-ahead position. And strangely, while the VW Group has opted to tune the suspension of the new Golf for the UK, for the moment it has elected not to do so on the A6. But such a move hasn't been ruled out as a future option, depending on the reaction the car receives here.

Much better is the interior - there's so much rear legroom now, courtesy of the long wheelbase, that the model is nearly as spacious as the A8. As you would expect with an Audi, the build quality is second-to-none and the ergonomics are spot on, too.

The A6 gains the firm's acclaimed MMI operating system, which simplifies the numerous controls for the sat-nav, air-con and stereo. It's very intuitive to use, and knocks BMW's iDrive into a cocked hat. Indeed, our only criticism of the cabin concerns the colour of the dashboard plastics, which were a bit too grey in our car. Even the aluminium inserts failed to lift the dull shade.

Prices for the new model start from £24,175 for the base 2.4-litre version, and rise to £42,775 for the top-of-the-range 4.2 quattro. Our 3.0-litre turbodiesel sits right in the middle, and with its impressive fuel economy and refinement is the pick of the A6 range.