Compare the Ford Fiesta ST 1.5 Turbo 5 door - [2018] vs Mercedes SL Class 450SL V8 R107 - [1975]. 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 Ford Fiesta ST 1.5 Turbo 5 door or the Mercedes SL Class 450SL V8 R107. We'll leave it up to you to decide which is your favourite.