BMW presents quad-turbo diesel

BMW’s famed, multi award-winning triple-turbo six-cylinder diesel engine is under threat of extinction.

The Bavarian car-maker showed its replacement recently at the industry-only Vienna Motor Symposium and while it retained the company's famous inline six-cylinder engine layout, it picked up yet another turbocharger.

Said to be due for production use in the M750d xDrive early next year, the quad-turbo diesel inline six will supplant the tri-turbo engine (pictured) in everything from the M550d xDrive to the same M Performance Automobiles-spec powertrains in the X5 and X6.

BMW, which has emerged from Germany’s diesel emissions-cheating and loophole-finding scandals relatively untouched, hasn’t given up on diesels just yet, it seems.

While details are scarce, BMW is not claiming mountains more performance, it’s claiming a lot more throttle response and drivability all the time.

The quad-turbo motor will have 290kW of power, which is only 10kW more than the current M550d xDrive can boast of, and exactly the same 740Nm torque peak figure.

The tri-turbo version of the 3.0-litre six uses a small turbocharger to deliver torque at very low revs, then another one to take over as the revs rise towards the torque peak, followed by a variable-geometry large turbocharger to take care of the power peak and delivering a linear feel.

First reported last year, the new motor retains the two small turbochargers, but adds a second larger turbocharger, though BMW isn’t admitting whether they work sequentially or in tandem.

BMW reportedly suggested in Vienna that the new layout will lower fuel consumption by around five per cent, cutting into the existing M550d xDrive’s 6.3L/100km figure on the NEDC cycle.

But whether or not BMW finally relents and delivers the big motor in right-hand drive is anybody’s guess.