The original ‘Scat Pack’ cars were named after scat’s also original slang meaning: to leave quickly. This was common in fifties and sixties movies: someone yelling scat at someone else, or a cat, to induce the other to leave. So the scat pack cars were there to leave quickly, ie go fast, which is pretty much what sports cars do.
I think that meaning is almost entirely gone, but the name remains. Meh. Linguistic evolution.