War's Car

Horsemen in lore were noted to have ridden horses. In Supernatural, they have moved on with the times and now drive cars.

War, as the Red Horseman, rides a red 1965 Mustang Fastback. It has Colorado plates which read 971-Q4S.

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