Green’s Dictionary of Slang

(US black) a Cadillac Coupe de Ville.

1980		E. Folb Runnin’ Down Some Lines 84: The Cadillac – variously referred to in the vernacular [...] by special model names, the B (Brougham), El D, Rado, slingshot (El Dorado), D. V. or coupe (Coupe d’ Ville).
2000		Hip-Hop Connection Jan./Feb. 54: Commonly abbreviated to Lex as in the Lost Boyz’ ‘Lex, Coups, Bimaz And Benz’. You can find out all about those other cars yourself.