Compare the Audi A6 RS6 5.0 TFSI V10 - [2008] vs Audi A8 S8 Plus 4.0 V8 Turbo - [2016]. 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 Audi A6 RS6 5.0 TFSI V10 or the Audi A8 S8 Plus 4.0 V8 Turbo. We'll leave it up to you to decide which is your favourite.