Compare the Mercedes GT R 4.0 V8 Bi-Turbo - [2016] vs Porsche 911 GT2 997 - [2007]. 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 Porsche 911 GT2 997. We'll leave it up to you to decide which is your favourite.