Audi is planning to launch a 500 horsepower, 6.0-litre V12 version of the Q7 off-roader, which will become the world's most powerful diesel passenger car.

Audi says the car will accelerate from 0-62mph in 5.5 seconds, and on to an electronically-limited 155mph.

Yet Audi says it will be able to deliver 23.7mpg on the combined cycle.