The continued downward spiral of emissions isn’t limited to the more popular fleet models because the niche players are also getting in on the act.

BMW‘s new 6-series Coupe is available with what the company describes as the world’s sportiest diesel engine. The 313hp 3.0-litre twin-turbo unit in the 640d is capable of taking the car from 0-62mph in just 5.5 seconds. That’s all well and good, but it also manages to return 51.4mpg and offers a CO2 emissions figure of just 144g/km, less than a 2.0-litre diesel Kia Sportage.

The 640d is a rapid, handles well and is about as practical as a coupe comes, with decent rear passenger space and a 460-litre boot. Good levels of standard equipment include a leather interior, eight-speed automatic transmission, satellite navigation, Xenon headlamps and front and rear parking sensors, while the £4665 M Sport pack adds muscular styling, sports seats and a host of premium detailing. At more than £66,745 the 640d is not cheap, but those that can afford it are getting quite a car.

BMW 640d Coupe M-sport
P11D price £66,560
Model price range £59,565-£71,840
Fuel consumption 51.4mpg
CO2 (tax) 144g/km (22%)
BIK 20/40%
per month
£244/£488
Service interval variable miles
Insurance (1-50) group 47
Warranty 3yrs/Unlimited mls
Boot space 640litres
Engine size/power 2993cc/313hp
Top speed/0-62mph 155mph/5.5secs
On sale October 2011
Score 8/10
Verdict Not cheap, but
impressive for
performance,
efficiency, looks
and practicality
for a Coupe