ACDelco is an American automotive parts company. Over its long history it has been known by various names such as United Motors Corporation, United Motors Service, United Delco, merged with AC Spark Plug and known as AC-Delco.

United Motors Corporation was formed by William C. Durant in 1916 as an automotive component and accessory holding company. Durant was the owner of Buick and founder of General Motors in 1908. After he lost control of General Motors in 1910, he subsequently founded Chevrolet in 1911 with Louis Chevrolet and the profits from this permitted him to regain control of GM in 1916. At approximately the same time, he assembled United Motors.

Durant's founding of United Motors has parallels in his earlier experience in the horse-drawn carriage industry in Michigan. In the late 19th century he was co-owner of the Durant-Dort Carriage Company, one of the nation's leading carriage manufacturers. Concerned that they could not source components and raw materials at affordable prices or in sufficient quantities, Durant-Dort created a vertically-integrated operation owning hardwood forests and manufacturing its own bodies, wheels, axles, upholstery, springs, varnish and whips.