NO doubt you have read in numerous motoring tomes that a certain car is a ‘continent (insert Clarkson-esque pause and dramatic tone) crusher’: a large, luxurious and superfast car capable of sweeping across France and deep on into Tuscany with barely any effort.

Well, there are a few of these glorious beasts out there but few, I am willing to wager, are as eminently capable of propelling you from patisserie to pasta in super quick time than the Audi A8 4.2 TDI.

No doubt a Bentley or Aston Martin will do it in more style, but the massive Audi has not only the pulling power of a TGV, but the fuel economy of a family saloon. So you don’t have to stop as often and mix with the poor people at the services.

The 4.2-litre engine produces the most amount of horsepower in any production diesel car – 319bhp. It leaps to 62mph from standstill in 5.9 seconds and has a top speed limited to 155mph.

I had the good fortune to hang on to the wheel of one of these things as it beat a path through France to Le Mans to watch its diesel-powered cousin win the world’s greatest race.

We filled up 30 miles before the Channel Tunnel in Kent and refuelled, dustier, sunburnt and dehydrated, as the Eurostar deposited us back in Blighty 600 miles later.

That’s more than 30mpg, with four blokes, beer barrels and camping equipment on board.

For an executive who does a lot of business miles and wants supercar performance with a dash of reality thrown in, there is nothing that matches the 4.2 TDI.

True, £60,000 is a lot of money for a car, especially when a Mercedes-Benz S320 CDI, even in long wheelbase form is cheaper, but it does not have such a bestial engine. The A8 feels like a Boeing 747 at take-off.

Like the 24-hour-winning R10 TDI racer, the 4.2 V8 diesel is almost silent, has huge, predictable levels of grip (although the R10 does without the A8’s Quattro four-wheel drive system) and doesn’t need to refuel as often as the more raucous petrol-burning competition.

And that, on race track or road, makes for a winning combination.

Verdict

BIG luxury cars with this sort of phenomenal performance don’t find too many homes - users generally prefer to waft about. But the 4.2 TDI does have the unusual advantage of superb fuel economy for its size and speed which means for the lucky few, they will get the best of both worlds.

Max power (bhp/rpm): 319/3,750
Max torque (lb-ft/rpm): 480/1,600
Max speed (mph): 155 (limited)
0-62mph (secs): 5.9
Fuel consumption (mpg): 30.0
CO2 emissions (g/km): 249
On sale: Now
Price (OTR): £60,500