M06

Developed from the Model K for the Typ S of 1927, this was an overhead-camshaft six with the camshaft driven by a vertical shaft, two spark plugs per cylinder fired by magneto and battery both, and a Roots blower on the nose of the engine that was clutched in only for short bursts. Unblown it gave 120 PS; on the blower, briefly, 180. Boring it from 98 to 100 mm produced the seven-liter SS, and 6.2:1 compression took the best version to 170 PS and 225 PS.

The last step was the SSKL of 1931 — Supersport Kurz Leicht — where the blower ran permanently, compression reached 7:1, and the engine was rated at 300 PS at 3,400 rpm. As a racing two-seater it cost 40,000 Reichsmark, roughly nine times the price of a Mercedes-Benz 170 saloon. In Rudolf Caracciola’s hands it built the marque’s pre-war competition reputation almost single-handedly, and Manfred von Brauchitsch won the 1932 Avus race in a streamlined SSKL that a radio commentator christened a silver arrow. Fewer than 300 W 06s of all types were made.