It has been rumored since mid this year that the M5d is coming in 2012. It is clearer now that the model in question is 550dX, as revealed through a leaked dealer presentation in Holland. The car will be powered by new tri-turbocharged diesel engine with 3.0l inline-6 configuration, producing 381bhp and over 700Nm of power and torque figures. The drive will be channeled only via the AWD systems, as denoted by "X" in the car name. The car is expect to return around 46mpg matching of those on 535d.
The new tri-turbo diesel engine features a new setup consists of two traditional exhaust blown turbochargers in combination with an electrically driven turbocharger to added low-end response. Due to the massive torque, rear wheel drive is not even an option. BMW insiders hinted the century sprint to be around 5.0 seconds, thanks to gigantic torque and good AWD traction. Top speed will be limited to customary 250 km/h. There is also a performance oriented M550dX which will gets a hots of chassis and styling tweak by the M-division.
Production of the 550dX is expected to begin in March 2012. The new powerplant will also find its way into X5 and X6 model.