The Rover M series (or M16) is a line of 4-cylinder, DOHC internal-combustion engine introduced by the Austin Rover Group in 1986 for the then-new Rover 800 series. The M series was produced only in one cubic capacity – 1994 cc (2.0 L), and was a 16 valve development of the older British Leyland O-series unit first seen in 1978. For the Rover 800, there were two different versions, with single point fuel injection (for the Rover 820e) or multi-point injection (for the 820i). The M series uses the same cylinder block as the O-series unit as found in the Maestro and Montego, which mates with the Powertrain Ltd PG-1 manual gearbox. These were also used in the Morgan Plus Four, the only rear wheel drive application this engine was used in, meaning these can be put in rear wheel drive layouts u