In 1978 a sensational new sports car arrived on the scene to the delight of headline-writers and photographers everywhere. The mid-engined BMW M1 had no production car roots to report, its low, wedge-shaped body the original work of star Italian designer Giorgio Giugiaro. Soon it had its very own race series, the 470 hp Procar machines taking their place on the undercard of Formula 1 grands prix. Niki Lauda emerged victorious in 1979. 

All of this success emboldened the small squad of engineers to extend their endeavours increasingly to production cars, with particularly powerful examples of the 5 Series emerging in small numbers. The M535i, for example, had the 218 hp six-cylinder engine from the 635CSi Coupé under its bonnet. The Americans would call it a “sleeper” – a car whose enormous power was not apparent until you took it for a drive. Today it has long been the apple of many a collector's eye.