High Quality Content by WIKIPEDIA articles! The M20 is an inline-6 piston engine by BMW. Initially designated M60, the 12-valve, belt driven SOHC design was introduced in the 1977 BMW 520/6 and 320/6 as an entirely new design. With displacements ranging from 2.0 to 2.7 liters, it was the "little brother" to the larger BMW M30 engine. It had 91mm bore-spacing instead of 100mm of the M30. It was intended to replace the larger displacement 4- cylinder motors and was born out of BMW's conviction that a small six had more development potential than a large four (i.e. 2 liters+) Powering the E21 and E30 3-Series, as well as E12, E28 and E34 5 Series cars, it was produced for nearly two decades, with the last examples powering the E30 325i touring built until April 1993. By that time, the newer twin- cam M50 engines with 4 valves per cylinder had already been used in the E36 and E34 for a couple of years.