SOMUA developed in 1937 the SAu 40 self-propelled 75 mm gun. Its drivetrain featured an extra wheel to improve off-road capabilities, and the hull was wider. Only one prototype was built in this configuration; it fought in June, probably together with a small number of mass-production vehicles, fitted with the powerful 47 mm SA 37 gun, 72 units had been ordered on 1 May 1940. Designer M Bergman