Compare the Mercedes GT R 4.0 V8 Bi-Turbo - [2016] vs BMW 5 Series M5 Pure Metal Silver Edition F10 - [2015]. 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 GT R 4.0 V8 Bi-Turbo or the BMW 5 Series M5 Pure Metal Silver Edition F10. We'll leave it up to you to decide which is your favourite.