I just stumbled up on this site which has lots of 3D printable cars in the STL format. However I know nothing about the quality of their work but I thought I should post it here in case someone maybe interested.
Main web page
https://stlprintables.com/
List of over 130 Chevy bodies
https://stlprintables.com/product-category/chevrolet/page/1/
List of 255 Ford bodies
https://stlprintables.com/product-category/ford/
27 Buicks
https://stlprintables.com/product-category/buick/page/1/
And many other car makes as well.
It's kind of a good time waster for browsing.