Abilene's car...
... Is what model?.. I watched the film last night, and the motor sure stood out from anything else we heard... Sounded like a hell of a V8 burbling under there...
I've seen things you people wouldn't believe...
From the brief glimpse we get at the beginning of the film when he pulls up to the pool hall ( as we see it through the window ) it looks like a 1949 Mercury to me, just like Duane's later car.
255 CID "flathead" V8. They DO make a nice snorty bark and rumble with open exhausts, but were not that powerful for their displacement unless modifications were done to improve their breathing. If so, they'd be very quick cars for their era.