If two turbochargers are good, would three be even better? Apparently BMW thinks so. It's just confirmed that all four of the new breed of "M Performance" models it plans to present at the Geneva Auto Show in March will be fitted with an all-new, M-designed 3.0-liter diesel engine augmented by a trio of these performance-enhancing force-feeders in addition to the rest of their comprehensive enthusiast-oriented upgrades.

The heart of each of these BMW M Performance models - an M550d xDrive Sedan, M550d xDrive Touring, X5 M50d and X6 M550d - is a tri-turboed  inline-six diesel that uses advanced piezo-type direct injectors fed by an ultra-high pressure (2,200 bar) common-rail system to develop a stunning 381 horsepower and 546 lb-ft of torque -- the latter from as low as 2,000 rpm. Those figures make it the most potent oil-burner ever found in any BMW.

To optimize overall response and efficiency, the turbochargers are scaled -- two smaller high-pressure units with variable-vane geometry and a single  larger one that operates using lower pressure -- and function in a sequential manner with the first of the smaller turbos activating just off idle and the last and largest coming on at roughly 1,500 rpm. BMW says the additional turbocharger only adds about 13 pounds to the package compared to the conventional twin-turbo diesel six. The engine is backed by a specially modified version of the ZF eight-speed automatic, and the xDrive intelligent all-wheel-drive system in these M Performance line models also gets uniquely optimized settings. 

As for straight-line specs, the M550d xDrive Sedan can streak to 60 mph in 4.7 seconds while the M550d xDrive Touring needs only 4.9 ticks. On the Sport Activity Vehicle side of the equation, the BMW X5 M50d hits that benchmark speed in 5.4 seconds and the X6 M550d in just 5.3. All are electronically limited to a top end of 155 mph. In keeping with these eco-oriented times, BMW's new M-spec tri-turbodiesel is impressively clean and efficient. Beyond meeting stringent EU5/EU6 CO2 regs, it delivers projected combined economy figures that range between the U.S. equivalent of 30.5 mpg for the X6 M550d to 37.3 mpg for the M550d xDrive Sedan. In keeping with BWW tradition, each member of this new M Performance squad also gets its own comprehensively bespoke suspension enhancements as well as various cosmetic touches to the exterior and interior.

And now for the bad news. While BMW still intends to make M Performance vehicles part of its U.S. lineup at some point, none of this initial group of tri-turbo diesels are currently slated to make it to our shores. We're likely to hear a good deal more about the M Performance contingent at their formal reveal in Geneva, but for now, all we can do is hope that BMW has a change of heart.

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