A C63 with the performance pack (481hp) is running 3.7 to 60mph, 8.6 to 100mph and I believe (although my memory might be wrong) trapped 121mph in the 1/4 (C&D tested). The M3 would need a lot of add ons to be competitive with that. A base, non PP, C63 would be closer to an M3 with a tune I would bet.
But, as others have said, no one buys an M3 to drag race. The car is not intended to be the fastest in a straight line but, rather, to be one of the best overall cars... which it does very well.