Green’s Dictionary of Slang

(US black) any old car, both the original Capone-era models and more recent ones that lack the most up-to-date gimmicks and accessories and are thus de facto ‘old fashioned’.

1980

E. Folb Runnin’ Down Some Lines 112: I would call a gangster ride a big ride – Al Capone ride. [Ibid.] 228: Al Capone ride [...] 2. Any older-model car, with or without the latest car accessories.