Drive the C63 before you sell. I drove it first before I drove the M3 and I thought the M3 felt lighter and tighter. Love the C63 motor and rumble though I loved the M3 V8 a bit more, not in terms of power but an 8400rpm V8 is pretty rare.
08 GT500 convertible red package (Black w/ Red stripes) /Ford Racing Exhaust /Cold Air Induction 560hp
10 Porsche Cayenne GTS Black w/ Black Wheels 408hp
11 M3 Silverstone w/ Silver Novillo Leather /Tech /Premium /19" /DCT /Ipod 414hp