BMW introduced the 525 variant of their E12 5 Series for the 1974 model year. The 525 was fitted with BMW's M30B25V engine, which was a carbureted 2.5L inline six unit that used a single carburetor until 1975. This first evolution of the engine produced 143hp, but from 1976 onwards, the M30B25V received twin carburetors which boosted power to 148hp. This series of sedans were offered with a manual or automatic transmission sending power to the rear wheels. Production of the E12 525 ended in 1981, when the model series was discontinued.