BMW 7-Series

The cabin, especially the controversial iDrive system, remains a talking point. However, the fully electric seats are superb and provide all the comfort you could want while wafting along at 70mph at a mere 1,750rpm.

This is what a big executive car is all about - cruising in quiet, effortless style. Even with a 3.0-litre oil-burner under the bonnet, there's little engine noise at speed. Only on start-up and from outside the car are you aware that this 7 is a diesel. Our test car came with Dynamic Drive - a ΂£1,685 option which features electronically controlled dampers on the front and anti-roll bars on the rear to combat any lean when cornering. Despite this, a twisty road will soon show you that the laws of physics can't be beaten - after all, the 7-Series is a very large machine.

But when it comes to big company motors, the all-important tax question could be decisive in many a purchasing decision. Unlike Audi's V8 diesel A8 - driven in Issue 755 - the 730d slots into the 32 per cent tax bracket, three per cent less than any of the petrol models, thanks to a 227kg/km engine emissions figure. So there's less duty to pay if you opt for the 7, but Mercedes' faster-accelerating S320 CDI beats it with a 27 per cent rating. That could be worth thousands of pounds a year to a company driver.

However, if you're looking for the best yield on your investment, we would suggest waiting for BMW's all-new 5-Series, which goes on sale in the autumn. It's got the same engine that features in its bigger brother here, yet has a cheaper tax listing.