The GM Family I is a straight-four piston engine that was developed by Opel, a former subsidiary of General Motors and now a subsidiary of PSA Group, to replace the Vauxhall OHV, Opel OHV and the smaller capacity Opel CIH engines for use on small to mid-range cars from Opel/Vauxhall. The engine first appeared in the Opel Kadett D in 1979, and shortly afterwards in its Vauxhall badged sister – the Vauxhall Astra Mk.1 in 1980. Despite this, the previous Opel OHV engine continued to be sold in entry level versions of the Opel Kadett/Astra and Corsa throughout the 1980s.

The Opel OHV family is a pushrod inline-four engine. It was the first all-new engine developed by Opel of Germany after World War II and was released in 1962. Versions were in use through 1993.