Probably a used 1963 Pontiac Tempest convertible. It had a 4-cylinder that was half of a 389 with a 4-barrel carb. The transmission, quite likely outsourced from a Corvair, was in the rear end. Between transmission, clutch, and engine problems, it seldom ran right. Oh, it was the 1963 Motor Trend "Car of the Year".
http://en.wikipedia.org/wiki/Pontiac...1.E2.80.931963