Model tested: Audi A8 L
Price: £58,715-92,515
Date tested: July 15, 2010
Road tester: Craig Thomas

The Audi A8 L (for 'long wheelbase') has an extra 130mm added to its wheelbase, devoted to giving rear-seat passengers more space. Many criticised the standard A8's rear legroom, but not here. There's plenty of room and, if you opt for the reclining seats, you can really stretch out and get comfortable.

Things are made even better with adaptive air suspension system which controls the damping and adjusts the ride height.

Power comes from a range of two diesel and three petrol engines. The diesel range consists of a 3.0-litre TDI V6 unit producing 247bhp and 405lb-ft of torque, giving 0-62mph in 6.2 seconds and a limited top speed of 155mph. Opting for a V8 4.2 TDI means extra surge in the form of 345bhp and 590lb-ft, bringing the 0-62mph time down to just 5.6 seconds.

The 3.0 TDI is all the car most customers could ever want: the engine is extremely refined, only emitting a satisfying low growl when provoked by the throttle and its pace, helped by plenty of low-end torque, is surprisingly satisfying for such a big car.

Throw into the mix its 42.8mpg fuel economy and CO2 emissions of 176g/km and it starts to make a lot of sense. Its balance between comfortable luxury and affordable running costs has much to commend it.

The petrol engines will be a minority interest. The base model is a new supercharged 286bhp 3.0 TFSI V6 that hits 62mph in 6.2 seconds. The 369bhp 4.2 FSI V8 is quicker - 0-62mph in 5.8 seconds - and makes a satisfying and characteristically V8-like noise when accelerating.

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At the top is a monstrous 6.3-litre FSI W12 that does 0-62mph sprint in just 4.7 seconds, thanks to a 493bhp output and 461lb-ft of torque. It's difficult to see who would want a car this big and fast though.

Driving the longer A8 is a rewarding experience. It handles very well for something 5.3 metres long and weighing in at just under two tonnes, the Quattro four-wheel-drive providing plenty of grip when required and accurate steering that weights up nicely at higher speeds.

There's also a stack of clever active safety kit on board, plus all the toys required to keep passengers happy, including ambient lighting, an updated multi-media interface (MMI) with new touchpad, full MP3 capability, 20GB hard drive, digital radio, Bluetooth and options such as TV, DVD, internet access and rear-seat entertainment system.

The A8 L is entering a very competitive sector of the market, doing battle with the new Jaguar XJ, BMW 7-Series, Mercedes-Benz S-Class and Lexus LS600h for the senior executive pound. Highly refined, well equipped and very accomplished on the road, it's a serious contender and another step in Audi's progress towards its domination of the premium segment.