A project for an SPG to support light mechanized units. Designed from 1935 through 1937 on the basis of the S35 and S40 vehicles. The design featured a modified upper part of the armored hull with the 75-mm casemate Mle 1929 gun. The top of the cabin featured a single-seated turret with the 7,5-mm Mle 1931 machinegun. The mass production of the SAu 40 was requested in October 1939. A prototype (and, according to some historical sources, four more pilot SAu 40) were sent to the frontline and used in action in June 1940.
Characteristics are specified for vehicles with crews trained to 100%.