Officially presented at the opening of FIAT's Mirafiori plant in May 1939, the AB 40 was, at the time, something of a cutting-edge vehicle. Thanks to innovative solutions such as double drive and spare wheels mounted as neutral to help get over obstacles, it was a match for any foreign rival in the same class. The AB 41 version, introduced in 1941, included several improvements, yet its main weapon (a 20 mm Breda 35 cannon) remained the same.