The sheer scale of the new A8's launch was very fitting as the new luxury Audi goes straight to the top of its class as the largest in this rarefied sector. It's longer and broader than a Mercedes-Benz S-Class or BMW 7 Series, yet the new A8 is also lower to emphasise its proportions.

The next A8 stretches to 5,137mm in length and 1,949mm in width, but is only 1,460mm tall, which Audi reckons gives it a more sporting air than its immediate German rivals. Style-wise, the A8 appears very much in keeping with Audi's current trend and takes most of its cues from the current A4 saloon.

Audi has kept the aluminium construction of previous A8s for the new model, which now tips the scales at 6.5kg lighter than its predecessor. One of the weight saving measures is the fitment of new aluminium alloys that are stronger yet weigh less. Even the new LED headlights helps reduce overall weight while providing a brighter, whiter light.

A lower overall weight is even more impressive when you consider the amount of safety equipment Audi has fitted into the A8. It comes with a new safety system Audi calls Pre-Sense. This works in a very similar way to Mercedes' Pre-Safe technology by closing the windows and sunroof, pre-tensioning the seatbelts and switching on the hazard warning lights if the car senses an impending accident. Three different versions of Pre-Sense will be offered. The first slows the car and applies the brakes and the second does the same but with more force, while the third also moves the front seats forward to help better protect rear seat occupants.

There's more rear legroom than in the previous A8 thanks to the new model's extra length. In the front, the Multi Media Interface (MMI) controller has moved from the centre console to the main dash and comes with a revised touchscreen panel to make it easier to tap in phone numbers and use the satellite navigation. The gear lever has also been updated and is now a T-shaped lever set low and close to the driver.

The transmission in all new A8s will be an eight-speed automatic and quattro four-wheel drive is fitted to all models at launch. Air suspension is standard and an optional sports differential - similar to that seen on the Audi S4 - splits the torque between the rear wheels.

When the A8 is launched in March, it will be offered with petrol and diesel V8s. The 4.2-litre petrol V8 has 372bhp for 0-62mph in 5.7 seconds, while the 350bhp 4.2-litre TDi V8 is even quicker, covering 0-62mph in 5.5 seconds thanks to 590lb.ft of torque compared to the petrol's 328lb.ft. A 3.0-litre V6 turbodiesel will join the range later in 2010, producing 250bhp, and a less powerful 205bhp version will also be offered that emits just 159g/km.

Audi has yet to announce UK prices and says they will be revealed closer to the new A8 going on sale in March 2010.