I was under the (false) impression that BMW MT typically loses about 15% of crank hp. This is far less and a far more efficient drive train than I (most of us?) previously thought. 7% is impressive. I also thought (from various forums, etc.) that the 4WD Audis typically lose as much as 25%. Oh well wrong again, good to learn some new things all the time.
One other point to keep in mind is BER, if we don't get BER (rumored) it will put about 5-10 hp less to the wheels during acceleration compared to the EU cars. BER will obviously improve the 7% figure from the M5, but probably only by a small amount 1-2%.
Either way the 40 hp differnce at the wheels is quite impressive and this is the heart of what BMW means by "efficient dynamics" (not that BMW=2WD and Audi=4WD is anything new). This really highlights that the M3 should really smoke the RS4 on the Ring!