Colin Chapman's personal Lotus Cortina Mk2 DEV 565G in US TV series Pan-Am. Not quite a totally random background as it was bought and taken to NY for several years by one of the blokes who supplied cars to the series, so there's an explanation how it appeared.

This Bentley surely counts, http://imcdb.org/vehicle_655433-Bentley-R-Type-B77ZX-1954.html

even cooler considering its white, and now its in BRG with a stripe.

I'll always think of this even though it's not a background.
https://imcdb.org/vehicle_3430-Isuzu-VX-O2-2000.html

A triumph by Jale.
https://imcdb.org/vehicle_256144-Ford-Durango-1981.html

My find via another user's thumbnails from a previous account.
https://imcdb.org/vehicle_116666-Jeep-Grand-Wagoneer-SJ-1987.html

added here.
https://imcdb.org/vehicle_116944-Jeep-Grand-Wagoneer-Stretched-Limousine-SJ-1986.html

For something extra weird I found...a truck carrying a Big Boy restaurant display.
https://imcdb.org/vehicle_1510978-Mack-R-Series.html

I love the street-parked Daytona. Its predecessor the Charger 500 is even rarer: https://imcdb.org/vehicle_1931719-Dodge-Charger-500-XX29-1969.html

The only Plymouth Cricket station wagon on the site not from a documentary: https://www.imcdb.org/vehicle_175794-Plymouth-Cricket-Wagon-1972.html

US-spec TVR: https://www.imcdb.org/vehicle_68536-TVR-Vixen-2500-1971.html

Amphicar just chilling on a Los Angeles used car lot: https://www.imcdb.org/vehicle_1115736-Amphicar-Model-770.html

1958 Dodge with a hot engine in a plain wrapper, in a junkyard: https://www.imcdb.org/vehicle_1055002-Dodge-1958.html

One of 641 special edition Rams https://imcdb.org/vehicle_1956791-Dodge-Ram-2008.html (I count stuff like this, I love a good random special edition!)