About 40+ years ago I got a plaster sprint car for my kid. It was about 18" long & 12" high came as plain white plaster. He painted it and it hung on on his wall for years. I don't recall ever seeing a modified or stock car casting.
On that same note, when I was a kid they sold little plastic stock cars for 25 cents, styled like a 40 Ford coupe. Maybe 6-8 years back I ran into a fella that had the molds for that plastic stock car, about a year later he was selling them at Wall's Turkey Derby, I bought a 1/2 dozen of them.