War, as the Red Horseman, rides a red 1965 Mustang Fastback. It has a Colorado plate which reads 971-Q4S.
Horsemen in lore were noted to have ridden horses. In Supernatural, they had moved on with the times and drove cars.
Appearances
Trivia
Though the color isn't known, Kripke originally wanted the brothers to ride a 65' Mustang. He was convinced by his neighbor to switch to the 67' Impala. Source