The first of the BMW 5 Series was established in 1972 by BMW AG as the successor of the "New Class" E115 on the market. The designer of Paul Bracq designed vehicle has the model number designation E12. This first BMW 5 Series was offered only as a Four. He oversaw a reorganization of the nomenclature at BMW On.

For the E12 was a rich engine program - starting with the small 1.8-liter engine in the 518, which is already out of the BMW 1800 was known to the powerful 3.5-liter engine in the end of the series in small Circulation built M535i. BMW 518 and BMW 520, the best four-cylinder engines of the type M10. In 1977, the BMW 520 with the newly-developed small six-cylinder engine equipped M20. The variants of the swept volume increased 5 BMWs were with the big six-cylinder engine equipped M30.

A diesel engine, there was the BMW E12 yet, as the company up to that time diesel is not yet in the program had. The relatively heavy diesel engines of the 1970s, sometimes even without much turbo, did not fit into the dynamic concept of BMW. Surprisingly, when the successor model of a diesel E28 (M21) offered by the M20 engine was derived.