Our spy photographers have once again managed to catch BMW's upcoming 2011 M5 sedan undergoing testing in Europe.
Although this particular mule is still heavily camouflaged, we can see several pieces of traditional M-trim including widened fenders, massive cross-drilled brake discs, and quad tailpipes.
The current M5's 500 bhp 5.0-liter V10 engine will be replaced by the new 555 hp twin-turbo 4.4-liter V8 from the recently introduced X5 M and X6 M. There is speculation that the V8 could be retuned to produce upwards of 600 hp in the M5, but that remains to be seen.
As we have previously reported, the 2011 M5 could adopt a kinetic energy recovery system (KERS) similar to what is used in Formula One racing. Designed to capture energy that would normally be wasted, the supposed system would deliver additional boost for added performance.
Another green technology that could appear on the M5 is a variable displacement system which would deactivate several of the engine's cylinders for improved fuel efficiency.