BMW M Diesel Features BorgWarner Triple Turbo System

The 6-cylinder oil burner that powers BMW AG's new line of diesel-powered M models features a triple turbocharger system supplied by BorgWarner Inc.

BMW began introducing the new M Performance line variants of its 5 Series sedan and X5 and X6 crossovers for European customers this summer. None of the models, whose prices begin at $103,200, is expected to reach the American market.

The three-stage 3.0-liter diesel was developed specifically for the new lineup. The engine makes 381 hp and 546 lb-ft of torque a record high output for an inline six, according to BorgWarner.

The supplier's trio of turbochargers begin to boost air intake at engine speeds slightly above idle and continue to enhance output to the powerplant's 5,400 rpm limit.

The first of two high-pressure variable turbine geometry turbos kicks in as soon as the engine comes off idle. At higher engine speeds, that air-cooled unit is joined by a larger, water-cooled low-pressure turbocharger. Maximum acceleration activates the second high-pressure turbo.

BMW says the three-stage diesel is 24% more powerful and 8% more fuel efficient than the dual-turbocharged version of BMW's 3.0-liter unit. Specific output for the new engine is 125 hp per liter compared with 101 hp per liter for the two-stage powerplant.

BMW says the M diesel can propel its M550d xDrive sedan from zero to 62 mph in 4.7 seconds, yet average 37 mpg on the European test cycle.