Compare the Pontiac Firebird 455 4.7 L V8 - [1971] vs Ford Mustang 428 Cobra Jet 7.0 V8 - [1968]. 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 Pontiac Firebird 455 4.7 L V8 or the Ford Mustang 428 Cobra Jet 7.0 V8. We'll leave it up to you to decide which is your favourite.