Compare the McLaren 540C 3.8 V8 Twin Turbo - [2015] vs Mercedes SL Class 63 AMG Cabriolet - [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 McLaren 540C 3.8 V8 Twin Turbo or the Mercedes SL Class 63 AMG Cabriolet. We'll leave it up to you to decide which is your favourite.