The logical choice is the 640d which returns an average of 51.4mpg. Remember this car can complete the benchmark sprint in 5.5 seconds. BMW dealers can be expensive but you will get a first-class service to counter the outlay.

At 145g/km of CO2, the 640d is actually a reasonably clean car. This has been helped by the introduction of Efficient Dynamics technologies in the Coupe range and the all-new ECO PRO fuel saving mode. You can choose the ECO PRO by flicking the Drive Dynamic Control knob. Enabling ECO PRO tweaks the engine management system, accelerator mapping and gearshift characteristics in favour of a relaxed and low-revving driving style.

This reduces emissions and improves fuel economy.

BMW build quality is decent. The 6-Series has a good reputation for reliability but the previous generation had a few recalls. In 2004 it was recalled after reports of a loss of engine power. In 2006 there were two recall: loss of pressure in the rear tyres and the possibility of a rear shock absorber mounting failing. While in 2008 it was recalled for a rear axle carrier.