I'm curious why everyone says the "handling" on the M3 is better? On the track, yes, I'd agree. But on the road, commuting back and forth, does "handling" really come into play that often?
Since I drive both the C63 sedan and an M3 coupe, I just think the handling comment is a bit overused.
For those who have not driven a C63, it does handle quite well. Chuck it into an off ramp and you'll be surprised at the grip/composure.
Both fun cars, but not as different as the masses would have you think.