Compare the Ford Mustang GT 5.0 V8 Convertible - [1985] vs Vauxhall-Opel Kadett 2.0 16V GSi - [1988]. 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 Mustang GT 5.0 V8 Convertible or the Vauxhall-Opel Kadett 2.0 16V GSi. We'll leave it up to you to decide which is your favourite.