Paris show: Audi announces A8 V12

AUDI has thrown down the gauntlet to Mercedes-Benz and BMW with a 12-cylinder version of its A8 flagship.

The new aluminium, 6.0-litre W12 engine develops 309kW and a stump-pulling 550Nm, distinguishing it as the most potent powerplant available in any production sedan.

Audi says the new A8 L 6.0 quattro can sprint from standstill to 100km/h in less than six seconds.

But perhaps more impressive is the fact it can reach its electronically governed top speed of 250km/h after scarcely 38 seconds.

The bad news is that the newcomer is not destined for Australia at this stage.

Audi is currently the only manufacturer to use a 12-cylinder engine in the form of a double "V" or "W" in series production.

The manufacturer says the W12 is as compact as a V8 and significantly smaller than a conventional V12 engine.

This engine can only be combined with quattro four-wheel drive because of its unusually short length of 513 millimetres and width of 690 millimetres.

Audi claims all other 12-cylinder engines installed at the front of the car can only drive the rear wheels.

The extensive use of light metals such as aluminium and magnesium means the new flagship tips the scales at 1980kg, lighter than any of its competitors.

The W12 is formed by combining two ultra-compact V6 units. Each of the two cylinder rows contains six cylinders at an angle of 15 degrees.

Visual clues differentiating the 12-cylinder A8 from its lesser siblings include a grille with vertical chrome bars and W12 emblems on the front, flanks and interior of the car.

The bootlid is adorned by A8 L 6.0 quattro badging. Keen car spotters will also note the car's different tailpipes.

It rides on 18-inch forged aluminium wheels of 10-hole design shod with 245/55 ZR18 tyres.