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.
2015 Austin Yellow M4 | Black Full Merino Leather | DCT
2014 Corvette Stingray | Z51 | Torch Red | 7MT - Sold
2012 C63 Coupe | Performance package | Obsidian Black - Sold
2011 E92 M3 | Jerez Black | Fox Red | DCT | Competition Package - Sold