Volkswagen Phaeton TDI

One of the most effortlessly fast luxury cars ever, the Phaeton V10 TDI makes no apologies for stopping next to the black nozzle at filling stations. It is more than capable of taking on its petrol rivals on equal terms, and lays a very strong claim to being the finest diesel model on the planet.

Check out these statistics: two turbos, 308bhp and a whopping 750Nm of torque. Only Bentley's Arnage and the Mercedes S600 can offer more pulling power. But this Phaeton isn't a gas-guzzling petrol-engined machine - it's a diesel.

Powered by a 5.0-litre V10 TDI, the VW flagship is the world's fastest production oil-burner. It channels its huge thrust to the road via a standard-fit six-speed auto gearbox and 4Motion four-wheel drive, combining a limited top speed of 155mph with a 6.9-second 0-62mph time. And the most impressive figure? An average of 24.7mpg.

Yet no matter how good the statistics look on paper, on-the-road performance actually feels even faster. From idle speed upwards the V10 gives massive acceleration. As with all diesels, it does not 'live to rev', and there is little point venturing beyond the 3,750rpm peak power point. But the smooth box's tall gearing makes for supremely relaxing cruising - 80mph equates to only 1,900rpm. Oil-burners are never as quiet as petrol units, but although noticeable, the V10's sound is pleasant - a sort of gruff rumble under acceleration, fading to near silence when cruising.

Dynamically, the VW is a supremely comfortable mile-muncher rather than a sports saloon. On motorways it is outstanding, thanks to a well damped ride and excellent stability. The air suspension has electronically variable dampers, and set at 'soft' the Phaeton smooths out large bumps. Predictably, the sportiest position gives the best results on bends, if a more abrasive ride.

But driving is only a small part of the attraction. Any journey is an opportunity to experience one of the world's best cabins. Superb multi-adjustable leather seats and ergonomics, plus four-zone climate control, are all standard.

The V10 TDI will be offered with either four or five chairs, and there will be a long-wheelbase version, too. VW looks to have caught its German rivals on the hop - both BMW and Mercedes have V8 turbodiesels, but don't bring them to the UK. Expect rival makers to rush to pick up the Phaeton's gauntlet...