 There was actually four 440 Challenger R/Ts and one 383 Challenger  R/T, which was an automatic with green interior. This one was used  for some exterior shots and it pulled the 1967 Camaro up to speed so  the Camaro could hit the bulldozers. As confirmed by property master  Dennis J. Parrish (qv), all of the cars were NOT originally white.  They were just painted white for the film. During the scene where  Kowalski has a flat tire, you can see green paint in the dents.