On the eve of BMW's domination of the 2005 International Engine of the Year awards, Audi announced the launch of what it claims to be the world's most powerful production diesel engine with some pretty serious numbers being batted around.

The 4.2-litre V8 TDI engine supersedes the 4-litre unit, and has a lot more power (320bhp vs. 270bhp). The incredible peak torque figure of 479lb.ft is available all the way from 1600rpm to 3500rpm delivering 0-62mph in only 5.9 seconds on its way to an electronically limited top speed of 155mph. In-gear acceleration promises to be shattering, despite hauling the large A8 saloon around. Perhaps just as remarkable are the claims for 30mpg on the combined fuel economy cycle, allowing a cruising range of nearly 600 miles.

For now, the 4.2-litre engine will only be fitted to the A8, in either standard or long wheelbase versions. Prices for the standard car start at £58,605, with the longer car starting at £61,975 on-the-road. There does not appear to be a proper competitor for this car in the UK. BMW does a V8 diesel on mainland Europe for its 7-series, but that car is not imported to Britain, and the only offering from Mercedes-Benz official channel is an S320 CDI.

Hopefully we'll get behind the wheel of this new super diesel before the end of the year. Watch out for the review on the main Road Tests page.

Shane O' Donoghue - 2 Jun 2005