With this in mind, fitting the DMS kit to a 330Cd (or indeed a 330d saloon) seems to make a lot more sense. This car produces a claimed 260bhp and 410 lb ft, up some 50bhp and 100lb ft respectively, taking the output very close indeed to the performance of the twin-turbo.

The car we drove was DMS's own 330Cd auto demonstrator. To begin with, everything was normal, except that corners kept arriving slightly earlier than expected - the lazy nature of the big diesel fools you into thinking you're travelling slower than you actually are, thanks to the laid-back soundtrack.

So we made the journey to Bruntingthorpe and strapped the test gear on to find out what the true performance gains are. A standard 330Cd gets to 60mph in a little over 7sec, which is no mean achievement. But even on the first run the DMS demolished these figures, producing a best of 6.1sec to 60mph and 16.3secs to 100mph (over 3sec quicker than the standard car). We eventually brought proceedings to a halt at 144mph as we were about to run out of runway. And all this in an auto - the manual would be a few tenths quicker still.

The DMS conversion makes a pretty convincing case for itself. It delivers a massive improvement for the outlay of ΂£595 and would seem a bit of a no-brainer if you're hooked on diesel. You can contact DMS on 01264 729016.