The current N57 performance diesel is called the M Performance TwinPower Turbo. The new one, said to be codenamed B57 TOP, will first make its way into the new 7 Series that will be called the M750d. The coming quad-turbo diesel is expected to produce at least 400 hp and 590 lb-ft. It isn't known yet whether the additional turbo will be electric or conventional, nor how the new turbos will be sized relative to one another. At least one outlet figures the power numbers will be conservative for this first outing, so they could go up. After its launch in the 7 Series, it could migrate to create the next-generation G30 5 Series M550d, and the X5 M50d, X6 M50d, and X7 M50d. It's unclear if BMW has plans to bring this high performance engine to the US market.