I think I'm going with the '64 Malibu in Repo Man. Ryan had never heard of Repo Man, which made me feel old. Here's some trivia on the car from IMDB:
When filming began, they only had one 1964 Chevy Malibu. It was stolen a couple of days into filming, forcing the film crew to scramble to find a replacement. Shortly after finding a replacement, the original was recovered by the police undamaged. This was fortunate timing because about a day later Fox Harris severely damaged one of the Malibus by accidentally plowing it into a gasoline pump! In the carwash scene, one of the gas pumps is clearly severely dented up and damaged. This is the pump Fox plowed into in a previous take.
No special effects were used to make the Chevy Malibu glow while parked at the repossession lot. Instead, the car was completely coated with 3M reflective paint, at an approximate price of $600 per bucket.
So what's your favorite car from an 80s movie? Post a link to a pic!