Cadillac fins phenomenon is a real story that came from the Chief designer of GM, which happen to be a guy named “Harley Earl. One day he stopped right in front of a Lockheed P38 fighter air-craft, a three-fuselage combat plane, with two of its fuselages ending in a graceful fin. The idea occurred to him to use these excrescences on cars. And so it was that ”prefins” appeared on the 1947 Cadillac to become veritable protuberances in 1948.