Compare the BMW 6 Series M6 Gran Coupe 4.4 V8 F06 - [2015] vs Porsche 911 Carrera 4 GTS PDK Cabriolet - [2014]. 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 BMW 6 Series M6 Gran Coupe 4.4 V8 F06 or the Porsche 911 Carrera 4 GTS PDK Cabriolet. We'll leave it up to you to decide which is your favourite.