5: Ford Mustang II
As the muscle car era was coming to an end and the fuel crisis was happening, Ford had to act fast. The pony car was fun to drive, but Ford had to increase fuel efficiency. The Mustang II was based on one of the worst cars ever, the Pinto. Still, the underrated Mustang II had some pretty special features such as a King Cobra option. The lightweight design with a V8 helped things out.
Whichever way that you look at it, the Ford Mustang II was an underrated pony car. There was a lot of potential, but the Pinto design deterred a lot of buyers. The Mustang II is one of the rarest examples of the Mustang and a clean example is still a classic ride.