Rumours are that the M5 F10 will have the 4.4 twin-turbo V8 of the X5 and X6 M.
But I seriously hope the M5 doesn't sound anything like this...
... because it sounds horrible.
It doesn't sound like a twin-turbo V8 it sounds like a four cylinder; a turbo four cylinder but a four cylinder nevertheless. I wish it sounded deeper and more thunderous like Mercedes-Benz AMG's new 5.5 twin-turbo V8:
http://www.mercedes-amg.com/privatel.../M157_Idle.wav
http://www.mercedes-amg.com/privatel...57_Revving.wav
http://www.mercedes-amg.com/privatel...lling_Away.wav
http://www.mercedes-amg.com/privatel...celeration.wav
http://www.mercedes-amg.com/privatel...57_Passing.wav