Compare the Mercedes S Class 65 AMG Cabriolet 6.0 V12 - [2017] vs Porsche 911 GT3 996 - [2003]. 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 S Class 65 AMG Cabriolet 6.0 V12 or the Porsche 911 GT3 996. We'll leave it up to you to decide which is your favourite.