Green’s Dictionary of Slang

(US black) a Mercedes Benz automobile.

1986		in Morning Call (Allentown, PA) 18 Aug. n.p.: Benzo: Mercedes-Benz [HDAS].
1992		D. Burke Street Talk 2 27: How much did you pay for your Benz-O?
2002		‘Touré’ Portable Promised Land (ms.) 182: Flying down Manhattan’s West Side Highway at 95 miles an hour, slaloming around Fords and Benzos as if they’re little orange cones.
2005		ClassifiedAds.com 13 May 🌐 Category: ALL > Cars & Trucks > Foreign Cars > Mercedes-Benz. extremely fast old benzo.