NASCAR’s Rulebook Forced Mercury to Build 503 Street Cars in 1969 – Today Fewer Than 75 Are Known to Exist by Jack Harmon Mercury’s 1969 Cyclone Spoiler II only exists because NASCAR’s homologation rules demanded 500 street cars for every race car. Decades later, fewer than 75 of the 503 built — split between two NASCAR driver tribute trims — are known to survive.
