Audi A8L 6.0 quattro

By combining the A8's lightweight alloy body and the awesome W12 powerplant, Audi has created a fast, refined and fairly economical super-saloon. The engine may be relaxed, but it hides some serious pace. Throw in the peerless build and usable technology and you have a highly desirable luxury model. Just make up your own mind about the new styling.

It takes a while to realise just how refined the Audi A8 W12 really is. It's not when you first turn the key and hear the faint rumble ahead of you, or even when you hit 70mph for the first time. Rather, it's when you operate the windscreen washer - because at motorway speeds, the most deafening sound is the electric motor squirting the headlights clean.

Audi has shoe-horned the biggest, baddest VW Group W12 into the A8's engine bay. This is the same basic unit as seen in the Bentley Continental GT, although in this instance it isn't turbocharged and produces 444bhp and an impressive 580Nm from 4,000rpm.

And that's plenty of power for the A8's weight. Because even though this is a long-wheelbase version, it tips the scales at less than two tonnes as a result of the Audi's use of aluminium - 400kg less than the Bentley. So the 0-62mph dash takes 5.2 seconds and the top speed is limited to 155mph - which is slower than the outrageous Mercedes S600, but still pretty quick for such an enormous luxury saloon.

These figures don't do justice to the feeling you get when you plant your right foot, though. This really is a very fast car and there's such a massive surge of power available that it's almost too effortless. At idle and under acceleration, the rumble suggests a hidden menace lurking beneath the bonnet, but relax at cruising speed and it becomes a near-silent comfort zone.

As well as the W12 engine, the A8 is the first model in the entire Audi range to wear the controversial shield-shaped grille surround. Reaction to this hasn't exactly been favourable so far, but it looks a lot better in the metal, and the same design is carried through to the new four-spoke steering wheel.

And other bright ideas are used for the headlamps. Besides having a direction capability to illuminate around bends when the steering is turned, the W12 is the first car in the world to use LED lamps for daytime running lights.

These are on all the time, but use minimal power, saving fuel and battery energy. When the low-beam xenons are switched on, the LED daytime lights are dimmed to make sure they don't dazzle other drivers. And whatever the safety advantages, the star-shaped lamps certainly look eye-catching, day and night.

Underneath, the car remains the same as the stock A8, apart from having air-suspension as standard. This means plenty of comfort on smooth surfaces, but not so much over rough tarmac. However, the brakes are better; they were a weakness on the previous W12, which was never imported here. Prices start from £75,775, so it's not cheap. But it is less than the S600, and more economical, too. While fuel costs might not be too much of a concern for buyers in this sector, the A8 should average 20.5mpg - and that's nothing short of exceptional for a car of such size and performance. By comparison, the Maserati Quattroporte driven in last week's issue returned only 14.9mpg. It may not be the most obvious choice, but the A8 is easily one of the finest cars in the world.