Haven't been on the forum for a while, so apologies if you have seen this before. read an interesting article in Autocar the other week about actual power available at the wheels against quoted power. Audi RS4 seems to be the main culprit losing a massive 68 bhp (16.5%) throught the 4 wheel drive transmission. The BMW M5 loses only 7% as it is 2 wheel drive. Should make for an interesting comparison if the E92 M3 has similar losses to the M5.
M3 - 385 bhp at the wheels
RS4 - 345 bhp at the wheels
Sounds like it could be an ass kicking for the RS4 to me (unless it's wet!!)