Compare the Ariel Atom Mugen - [2012] vs Audi A5 RS5 2.9 V6 Turbo Coupe - [2017]. 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 Ariel Atom Mugen or the Audi A5 RS5 2.9 V6 Turbo Coupe. We'll leave it up to you to decide which is your favourite.