BMW 7-Series

The UK will only get the 3.0-litre six-cylinder although Europe has the option of an even more potent 4.0-litre V8, but we needn't worry. The latest turbo six has lost weight, and updated common-rail injection technology gives extra power, improved economy and refinement that would shame many a petrol-engined rival. You'd never know it was a diesel, even starting from cold - it's smooth and incredibly punchy. We're talking 218bhp and 500Nm of torque, giving 146mph and 0-60mph in eight seconds. All this comes with 33.2mpg economy - and tax benefits.

Throw in world firsts such as the only turbodiesel with a six-speed automatic gearbox, and it's clear that the 730d has redefined a class.