BMW's amazing new 381 bhp 740 Nm 45 mpg triple turbo diesel (and four cars that will get it)
By Jack Martin
January 26, 2012
BMW M Performance is adding four new models to its product range, all powered by a new triple-turbocharger, piezo direct injection, three liter diesel motor that looks to be a contender for the engine of the year already - 280 kW, 740 Nm, instantaneous response, very economical, low emissions. The new BMW M550d xDrive, M550d xDrive Touring, X5 M50d and X6 M50d models will be seen first at the Geneva Motor Show in March with availability just a few weeks later.
The engine in BMW's new diesel M cars appears to be a ripsnorter - 3.0-litre six cylinder with three turbochargers, common-rail direct injection with piezo injectors, a very healthy maximum power output of 280 kW (381 bhp), but with abundant torque (740 Newton metres - 546 lb-ft) and instantaneous response
The dyno charts say it all. Look at that flat torque plot between 2000 rpm and 3000 rpm - 740 Newton meters of torque is almost an obscene amount of torque. It will give you goose-bumps. It is a performance motor that will almost certainly power next year's Dakar cars.
The key to the incredible performance of the engine is inaptly named M Performance TwinPower Turbo technology. That's because they found that two turbochargers worked so well together, that they have now employed three for the first time.
The system uses two smaller turbochargers and one large one, with the right diameter turbo being used at precisely the time when it is most efficient. Another reason why three turbos is better than two is that the low moment of inertia of the small turbochargers means they do not suffer from the lag of a larger single turbo.
if the interplay between the strategy of the turbos are designed to guarantee maximum power delivery across a wide rev band. The system comprises two relatively small turbochargers and one large turbo, which join forces precisely to deliver the amount of power required.
In the machines that are being released, the 280 kW engine delivers very respectable figures. All cars are electronically limited to 250 km/h, but the acceleration figures tell the tale.
The BMW M550d xDrive Sedan will accelerate from 0 to 100 km/h (62 mph) in 4.7 seconds - that's rapid for a car of this price that can still inspire confidence and safety when dropping the kids at school.
The M550d xDrive Touring does the 100 km/h dash in 4.9 seconds, the heavier X5 M50d and X6 M50d in 5.4 seconds and 5.3 seconds respectively.
The performance of the six-cylinder in-line diesel is only half the equation though.
Extensive application of BMW EfficientDynamics technology including an auto Start-Stop function have yielded some excellent fuel consumption and CO2 emission figures.
The BMW M550d xDrive Sedan with its lighter weight and lower frontal area, returns the best of the bunch with 6.3 litres/100 kilometres (44.8 mpg imp) and CO2 emissions of 165 g/km.
It's interesting to note the rapid fuel consumption dropaway with the extra weight - the similarly sized BMW M550d xDrive Touring returns consumption of 6.4 litres/100 kilometres (44.1 mpg imp) and CO2 emissions of 169 g/km, while the heavier BMW X5 M50d returns 7.5 litres/100 kilometres (37.7 mpg imp) and 199 g/km. The slightly sleeker and marginally lighter BMW X6 M50d fares little better at 7.7 litres/100 kilometres (36.7 mpg imp) and CO2 emissions of 204 g/km.
These cars come with a significant boost in performance and hallmark M precision in the interplay of the powertrain, chassis and aerodynamics - coupled with unrestricted everyday utility and high levels of efficiency.
The new powerplant strikes the most effective balance between output and fuel consumption of any series- produced unit of its kind.