Early versions were armed with a short barrelled 7.5cm assault gun but as a result of experience gained in the Polish campaign the armour was increased and detail improvements made to create the Pz KwIVF1. In 1942 the new long barrelled 7.5cm gun was introduced on the F2. In addition to the 7.5cm gun the Panzer IV carried two 7.92mm machine guns. The 300 b.h.p. Maybach petrol engine gave a maximum road speed of 24mph (38.40km/h).