There had been expensive, limited edition M-Series models before the M3 but it was the latter's arrival that brought BMW's premier performance brand within the reach of less wealthy enthusiasts.

The M3 resulted from BMW's need for a car suitable for Group A racing, the rules stipulating that 5,000 should be made in the first year of production.

By this time (the early 1980s) BMW's single-overhead-cam slant-four engine would have been hopelessly outclassed on the racetrack so the required power increase was achieved by bolting on a 16-valve cylinder head.

Bored out to 93.4mm, the Bosch fuel-injected M3 motor displaced 2,302cc and produced a class-leading 200bhp.

Although it looked pretty much like a standard E30 3-Series from a distance, the M3 shared only the bonnet with its less-exotic sibling.

Most obvious difference was the wider front and rear wings while only the most observant would have noticed the more steeply raked rear window and raised boot, changes made in the interest...