The european mags (CAR, EVO, TOP GEAR), based on some spy shots and their sources...they believe the C63 will trounce the new M3.
In EVO magazines Car of the Year
competition, a driver in the new Ferrari 599 GTB Fiorano was awe-struck by his first drop of the 599s hammer..."lung flattening and numbingly savage" acceleration he wrote. But he looked in his rearview mirror and there was the CLS63 (right on his ass)
Now think about that for a second. Then, think about that engine in a C class.
I think Mercedes is onto something!!
BMW is a foil...light, quick, efficient...MB/AMG is a saber (heavy, brutal, brutally effective). Both kill in different ways.
P.S. I didn't answer the OPs question...MB wins the drag race. And (big sigh), maybe around a track.