This really is the story of an engine, not just because it does things no engine has ever done, but because the less said about the car to which it is fitted the better. I have never cared for the ugly, proligate, heavy and expensive BMW X6 and that’s something not even the world’s best diesel engine can change.
To give you an idea of how far the BMW diesel engine has come in the past 20 years, in 1992 you could buy a 325td whose 2.5-litre six-cylinder motor used a turbo to boost its output to 116bhp. I can remember being amazed by its performance and reliability.
Now and with a gain of just half a litre in capacity, the 3-litre diesel in this X6 produces 376bhp. What’s more absurd still is that despite carrying almost an extra tonne of weight, official figures suggest the X6 uses less fuel.
I have my doubts about the latter contention but the performance is undeniable: this 2.25-tonne monstrosity will throw itself up the road to 62mph in 5.3sec – 20 years ago I seriously doubt there was a Ferrari in production that would stay with it.
What provides the highest specific output of any diesel engine is the itment of not one or two, but three turbochargers. For many years engineers have hotly argued the relative merits of twin turbos operating either in sequence or simultaneously, but only BMW envisioned the possibility to do both. So the X6 motor has two small turbos for quick response at low revs, progressively handing over to a far larger turbo to provide the requisite kick high up.
It works brilliantly: there’s no lag, simply enormous torque low down and absurd punch as the needle races around the clock.
The good news is the engine is also available in the far more practical, better looking, slightly cheaper and a lot less offensive X5. It would have some claim to being the ultimate performance SUV.
What is really needed, however, is for the engine to visit BMW’s more conventional and far lighter cars: imagine what it would be like in a 5-series. actually the car already exists, is damn near as quick as an M5 and uses less than two-thirds of the fuel. The killer is it’s only available with four-wheel drive (probably because it has even more torque than the M5), and four-wheel drive Fives are not made with right-hand drive. shame – an all-wheel drive Five Touring with this engine could be the most accomplished all-purpose weapon you can buy.
ENGINE: 3.0 litres, six cylinders, diesel
TOP SPEED: 155mph (limited)
POWER: 376bhp at 4400rpm
FUEL/CO2: 36.7mpg, 204g/km