The E30 M3 is the BMW Motorsport-developed version of the E30 3 Series. Its S14 four-cylinder powerplant is a further development of the M10 unit and was chosen by BMW because of its compact dimensions. The S14 engine powered the E30 M3 from 1986 to 1991.

The E30 M3's S14 engine was designed for racing applications and is therefore compact and high-revving. It combines the basic four-cylinder block from the M10 family with a four-valve head derived from the one used on the six-cylinder M88 and S38 motors. Special features of this engine include individual throttle plates for each cylinder, machined intake and exhaust ports, and a crankshaft with eight counterweights. Like the M88 and S38, the S14 does not have hydraulic lifters, and thus requires periodic valve adjustments.

The S14 engine developed 200 bhp, but a tuned variant with 220 bhp was created in 1989 in a small production run with the designation S14 EVO (for Evolution).

In Italy, BMW produced an 2.0-liter S14 version since cars with engines over 2.0 liters were subject to high taxes. To achieve 2.0 liters, the stroke was shortened to 72.6 mm.

In 1990, 600 vehicles were built with the S14 EVO2 engine. With a 95.5 mm bore and 87 mm stroke, the engine produced 238 bhp and competed successfully in the DTM German Touring Car Championships.