BMW 6-Series

BMW dieselfication of its coupe range goes all the way to the top. Well, all the way to the 6-Series, at least.

The ocularly challenging Six is set to go on sale with BMW's 3.0-litre twin turbo six-cylinder diesel engine and it will be called the 635d.

With 282bhp, the 635d does not disgrace the big coupe, managing 0-62mph in 6.3 seconds and hitting an electronically limited top speed of 155mph.

There's a six-speed auto as standard with flappy paddles for a sportier feel, but the 635d will still return 40.9mpg on the combined cycle.

At the same time the diesel engine is introduced, BMW is sneaking in a minor restyle of the Six.

You'll have to pay close attention to spot the larger front air intake, reshaped headlights with LED indicators, and boot lid that now incorporates a high level brake light.

Under the skin, BMW says the petrol 630i's engine is more frugal, while inside there's a simplified iDrive system for all models. Which means that people other than computer programmers and rocket scientists will be able to adjust the aircon temperature.

And every 6-Series now also comes with regenerative braking - à la 1-Series - to save fuel and energy.

No prices yet for the tweaked 6-Series, but expect the 635d to weigh in at more than 50 grand when it reaches the UK.