Compare the Ford Mustang GT 5.0 V8 Convertible - [1985] vs Oldsmobile Cutlass Calais HO Quad 4 - [1989]. 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 Oldsmobile Cutlass Calais HO Quad 4. We'll leave it up to you to decide which is your favourite.