400-hp quad-turbo BMW diesels just around the corner?
 

http://autoweek.com/article/car-news...-around-corner



NEW 7-SERIES REPORTEDLY WILL RECEIVE QUAD-TURBO 3.0-LITER INLINE-SIX DIESEL



Tri-turbos are sooo last season. Aiming to keep up with fashion BMW is reportedly working on quad-turbo engines, according to Autocar.



The Munich-based automaker already fielded a tri-turbo design in the X5 xDrive50d M Performance and the M550d, adding an electrically driven turbocharger for extra low-end boost pressure. The quad-turbo design could follow that with another electrically driven turbo, or BMW could opt to go the conventional route and simply add a second bi-turbo setup to the diesel inline-six.



The quad-turbo inline-six diesel engine is expected to debut in the M750d 7-series sedan in 2016, and it could also make a cameo appearance in the xDrive50d M Performance versions of the X5 and the X6 in the near term.



Just how much power is the quad-turbo 3.0-liter diesel unit expected to pump out? Autocar says we could see more than 400 hp and 590 lb-ft of torque. That'll be well north of the 255 hp and 413 lb-ft of torque that the outgoing 740Ld xDrive model -- the first diesel 7-series sold in the States -- produced when it arrived for the last model year of the F01-generation, whose run ended this year. That said, it remains to be seen whether the quad-turbo diesel will make it across the pond.



The 2016 BMW 7-series was revealed in June of this year, and is expected to go on sale in the U.S. by the end of 2015. The U.S. will receive just the long-wheelbase versions of the 740i and the 750i xDrive models, with the former using a 320-hp, 3.0-liter turbocharged straight six and the latter powered by a 4.4-liter twin-turbo V8 good for 445 hp and 480 lb-ft





Seems a little overboard. Couldnt you achieve the same power with a more efficient single or twin turbo?

When you're buying a BMW 7-series, it's no longer strictly about what you "could" do.

Quad turbo inline six? It must be basically a pair of sequential turbos. That's really the only way that makes sense. At what point is it not more cost effective to implement a KERS style electric to spool the turbos to 100k at all times so the spool to 150k is still solely achieved by the motor under stress.