Compare the Mercury Zephyr Z-7 Sports Coupe - [1978] vs Ford Mustang 2 Cobra 140 2.3 - [1978]. 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 Mercury Zephyr Z-7 Sports Coupe or the Ford Mustang 2 Cobra 140 2.3. We'll leave it up to you to decide which is your favourite.