The M-type was one of the first genuinely affordable sports cars to be offered by an established manufacturer, rather than as a modified version of a factory-built saloon or tourer. By combining an accessible driving experience with a low price — the new MG cost less than double the cheapest Morris Minor on which it was based — the M-type set a template followed by many subsequent MG models and by a broader tradition of small British sports cars through the 20th century.
The M-type used an updated version of the four-cylinder, bevel-gear-driven overhead camshaft engine originally fitted to the 1928 Morris Minor and Wolseley 10, producing 20 bhp (15 kW) at 4,000 rpm with a single SU carburettor. Drive went to the rear wheels through a three-speed non-synchromesh gearbox. The chassis was derived from the 1928 Morris Minor, lowered and fitted with half-elliptic springs and Hartford friction disc shock absorbers front and rear, with rigid axles and bolt-on wire wheels. Wheelbase was 78 inches (1,980 mm) and track 42 inches (1,067 mm).
The braking system on early M-types used a combination of rods and Bowden cables at the front and pure Bowden cables at the rear, with the handbrake acting on the transmission. The M-type could reach 65 mph (105 km/h) and return approximately 40 miles per gallon. The open two-seater was priced at £175 at launch, rising shortly to £185; a closed two-door Sportsmans coupé version cost £245.
Most bodies were supplied by Carbodies of Coventry and fitted by MG, though some rolling chassis were delivered to external coachbuilders such as Jarvis. Early bodies used a wood frame covered in fabric; from 1931 this was replaced by all-metal construction. MG also produced a small number of van-bodied versions for service use.
A series of updates arrived in 1930. The braking system was revised to a full Bowden cable arrangement without rods, and the handbrake was decoupled from the transmission brake. Engine output was raised to 27 bhp (20 kW) by improving the camshaft. A four-speed gearbox became available as an option, and the doors were changed to front-hinged opening. A supercharged version became available in 1932, raising the top speed to 80 mph (130 km/h) and priced at £250.
The M-type achieved considerable sporting success in its brief production life. MG works and private entries won gold medals in the 1929 Land's End Trial and took class victories in the 1930 Double Twelve race at Brooklands. The car was also entered in the 1930 Le Mans 24 Hours, though neither of the two M-types entered finished the race.
Early production took place at the Cowley factory; from 1930 it transferred to MG's dedicated facility at Abingdon. The M-type was produced until 1932 and directly succeeded by the J-type, which inherited the overhead-camshaft engine in refined form. The M-type's combination of low price, genuine sporting character, and small-capacity overhead-camshaft engineering established the formula that MG would refine through the Midget line for the following half-century. It demonstrated that a mass-manufacturer could offer a true driver's car at a price accessible to buyers who could not afford the larger and more expensive sporting machinery then available.