Not content with hanging three turbos off the side of a diesel inline six (as seen in the X5 M50d and X6 M50d), BMW has upped the ante by attaching a fourth turbo to its ubiquitous 3.0 diesel six-cylinder to create what is says is the world’s most powerful six-cylinder diesel - and the BMW 750d will be the first model to get it.
With peak outputs of 294kW and 760Nm, the 750d xDrive’s quad-turbo diesel produces enough power and torque to rival many modern performance V8 engines, yet it consumes just 5.7 l/100km on the European test cycle in standard-wheelbase form.
Thanks to AdBlue injection, a diesel particulate filter and NOX storage catalytic converter, emissions are held to a 149g/km
Three of the four turbochargers are constantly in operation - two low-pressure and one high pressure turbo.
Under hard acceleration the two low-pressure turbos are bypassed to channel more exhaust gas through the high-pressure turbo and build boost quicker, while a second high-pressure turbo becomes active above 2500rpm.
As a result, a huge 450Nm of torque is available from just 1000rpm. The full 760Nm whack is available from 2000-3000rpm and peak power occurs at 4400rpm.
All-wheel drive and an eight-speed auto are standard-issue on the 750d and long-wheelbase 750Ld, however if you were keen on the idea of a high-powered diesel limo of your own, best you don't hold your breath: BMW Australia tells us the 750d is not coming to our shores.
We may, however, see its engine in a future update of the X5 M50d and X6 M50d. Watch this space.