Insideline ‘s sources are echoing ours in reporting that BMW has decided to go with a high-output twin-turbo V8 for its next M5 due out in 2011.

As we ‘ve reported previously we expect BMW to introduce a “kers ” like system with this car as well as a new version of the DCT transmission found in the current M3.

Reasons for the V8 over the V10? Costs, efficiency, and packaging were all part of the decision.