Originally Posted by footie
Autocar tested both the RS4 and M3. The big surprise was that both cars were so evenly matched, right up to 150mph the only thing that separated them was 0.3s. So even with identical power, more weight and quattro the RS4 was only 0.3s slower to 150mph.
From all the videos I've seen the M3 pulls ahead quite a bit more than that. Check youtube