Compare the Mercedes C Class 63 AMG Coupe 507 Edition - [2015] vs Audi A6 RS6 5.0 TFSI V10 - [2008]. Find out which car is the fastest, most powerful, lightest or has the biggest engine in our top trumps style comparison page. Find out which car has the highest top speed or is the fastest accelerating, is it the Mercedes C Class 63 AMG Coupe 507 Edition or the Audi A6 RS6 5.0 TFSI V10. We'll leave it up to you to decide which is your favourite.