M950

Daimler-Benz opened a Wankel department in 1962 and put Wolf-Dieter Bensinger in charge; about a hundred rotary engines were built there over the following decade. The M 950 was conceived as a family around a 600 cm³ chamber, expandable on paper to six rotors — Bensinger noted that five would have loaded the eccentric-shaft bearings particularly favorably — though only three- and four-rotor versions were built. The housings were aluminum with a Nikasil coating developed by Mahle, the forged aluminum rotors weighed roughly half what cast steel would, and fuel arrived by mechanical petrol direct injection.

The C 111 shown at Frankfurt in September 1969 carried the three-rotor engine; the C 111-II at Geneva six months later had four rotors, 350 PS and a claimed 300 km/h. Durability was the problem nobody solved. Three-rotor units in the test cars failed at an average of about 3,700 km, through runaway oil consumption or lost compression, and none is recorded as reaching 6,000. A two-rotor version had been scheduled for series production in the W 114 in late 1970, with changes to the floor pan already worked in; it never came, and the redesigned M 951 took its place.