I'll come clean. I'm no diesel fan. I accept that the latest generation of super-diesels are often quicker than their petrol equivalents in terms of overtaking ability, that 'real- world performance' mantra that diesel-diehards live by. But for me the thrill of driving is found not when you're plodding through dense traffic, sneaking the odd overtaking manoeuvre - a discipline at which diesels excel - but when you're trying to escape from the 'real world' and enjoying everything a car has to offer, from the grip and balance to the sound of a sweet-spinning, eager engine. For which read 'petrol' engine.
I'm tired of hearing that 'diesels are the future of performance cars'. Maybe they are, but just maybe we should be celebrating the current breed of performance cars. You know, those with petrol engines. Anyway, I'll climb down from my soapbox now. And introduce this, the DMS-tweaked BMW 535d. A car that I'm reliably informed is a glimpse into the future, right here and now.
We've experienced the electronic wizardry of DMS on a number of occasions and know the quality of its work, but the claimed figures for the conversion on this 3-litre, straight-six twin-turbo are of the double-take variety. The 535d motor in standard form is already one of the very best diesel engines we've ever tried; it leaves the factory with a mighty 277bhp at 4400rpm and a Herculean 413lb ft at 2000rpm (more than the 5-litre V10 M5's 383lb ft). Some clever remapping by DMS liberates 344bhp at 4200rpm and a faintly ludicrous 506lb ft at 2570rpm, all for just £999. When you remember that the iconic Lotus Carlton, a car lampooned at launch for being unreasonably powerful for a saloon car, has 377bhp and 419lb ft torque, you begin to understand how far diesel technology has progressed. Independent test figures recorded at Millbrook Proving Ground reveal a 0-60mph run in 5.5sec and an astonishing 13.4sec sprint to 100mph. And did I mention it's an auto?
It feels faster. Much. And thanks to BMW's ingenious sequential turbo system (a tiny turbo ensures good low-rev response and a bigger turbo takes over as engine revs rise and more boost is required) the 3-litre diesel has a huge powerband, with meaningful urge from 1500rpm and real thump from as little as 2000rpm. Things only start to fade as you close in on 5000rpm - and with very long gearing (a sign of BMW's confidence in the engine in the first place) the 535d seems to take huge strides between shifts. More surreal is that whichever gear it snaps into there's simply more and more thrust. Only a supercharged AMG-product summons up a similar feeling that you're being swept along by a seemingly endless swell of thrust.
The Sport chassis does a pretty convincing job of translating sheer grunt into monster propulsion even in the lower gears and that tell-tale flashing yellow triangle rarely intervenes. Out of tight corners the 535d is beautifully hooked-up, and the combination of that elastic power-band and the grippy, flat-cornering stance make the 535d Sport an easy car in which to build up a rhythm. Unfortunately it's never quite as flowing as it could be; like all 5s save the M-version, this car suffers from an ill-composed ride, always jittery and easily wrong-footed by rapid-fire bumps. BMW admits the 5-series has suffered more than subsequent models from the fitment of run-flat tyres simply because the chassis was originally developed with standard rubber. You certainly sense that the dampers sometimes run beyond their capacity and have lost control of the weight of the wheel and tyre.
Other reservations include the overly heavy steering (this car isn't fitted with Active Steering), and the love-it-or-hate-it styling, neither of which DMS can be held responsible for. The conversion itself is faultless, the engine losing none of its flexibility but gaining an awful lot in usable power. DMS also claims that the reprogramming is completely undetectable by BMW diagnostic equipment, and adds it could easily have found more power but wanted to keep 100 per cent reliability. Even for a non-believer like me, this tweaked 535d is a compelling argument for the coming of a diesel revolution. If only they could stop it sounding like a Transit van...