Dad set me on a task to find out if the car in The Karate Kid (1984) is the same model car that Marty drives Lorraine in to the Enchantment Under the Sea dance in Back to the Future (1985).
Um, thank goodness for: Internet Movie Cars Database!!!
The answer: The Karate Kid car (above) is a 1948 Ford Super De Luxe. The BTTF car (below) is a 1948 Packard Custom Eight Victoria.