M951

When the coming mid-range car turned out to need a completely new front end — no subframe, different suspension — the two-rotor engine intended for it had to be reworked so heavily that it became a new type, the M 951. The redesign went after the faults that had killed the M 950: side housings in a low-expansion alloy for thermal stability, improved lubrication, aluminum rotors, a stronger cooling jacket. Mechanical direct injection gave way to Bosch K-Jetronic, and a stepped intake manifold attacked the rotary's weakest trait, its thin torque low down.

A four-rotor version followed on the same basis, over 350 hp, its induction tuned to pull properly from 2,000 rpm; a limited series of SL and SLC models was pencilled in for it, and the two-rotor cars were to go to selected customers so that the engineers could stay close to them in use. Then, in December 1975, the board ended both the launch and the development of the Wankel engine at Daimler-Benz. Thirteen years of work, roughly a hundred engines built, and not one of them sold.