Following on from this I picked up my 2010 C63 last week, very pleased with it, bought one with the Performance Pack Plus with LSD, engine output upgrade (SLS internals) etc etc. The thing does shift, even feels quicker than the SL55 it replaced!
Consumption wise on a normal 10+ miles run I get about 18-20mpg, on my 3 mile commute to the station I havent got it above 16mpg! Not as bad as I expected, the popping and banging on gearchange when accelerating hard is so addictive!!