Oldsmobile	8	1897-2005	Lansing, Michigan, United States
	Opel	73	From 1898	Rüsselsheim am Main, Hesse, Germany
	Orlandi	1	?-1988	Crespellano, Emilia-Romagna, Italy
	OSI	1	?-1968	Turin, Piedmont, Italy
	Otomarsan	1	1968-1993	İstanbul, Turkey
	Otoyol	3	1990-2008	İstanbul, Turkey