The Ausf. F tanks that received the new, longer, KwK 40 L/43 gun were named Ausf. F2 (with the designation Sd.Kfz. 161/1). The tank increased in weight to 23.6 tonnes (26.0 short tons). One hundred and seventy-five Ausf. F2s were produced from March 1942 to July 1942. Three months after beginning production, the Panzer IV Ausf. F2 was renamed Ausf. G.
During its production run from May 1942 to June 1943, the Panzer IV Ausf. G went through further modifications, including another armor upgrade. Given that the tank was reaching its viable limit, to avoid a corresponding weight increase, the appliqué 20-millimetre (0.79 in) steel plates were removed from its side armor, which instead had its base thickness increased to 30 millimetres (1.18 in). The weight saved was transferred to the front, which had a 30-millimetre (1.18 in) face-hardened appliqué steel plate welded (later bolted) to the glacis—in total, frontal armor was now 80 mm (3.15 in) thick. This decision to increase frontal armor was favorably received according to troop reports on November 8, 1942, despite technical problems of the driving system due to added weight. At this point, it was decided that 50% of Panzer IV productions would be fitted with 30 mm thick additional armor plates. Subsequently on January 5, 1943, Hitler decided to make all Panzer IV with 80 mm frontal armor. To simplify production, the vision ports on either side of the turret and on the right turret front were removed, while a rack for two spare road wheels was installed on the track guard on the left side of the hull. Complementing this, brackets for seven spare track links were added to the glacis plate. For operation in high temperatures, the engine's ventilation was improved by creating slits over the engine deck to the rear of the chassis, and cold weather performance was boosted by adding a device to heat the engine's coolant, as well as a starter fluid injector. A new light replaced the original headlight, and the signal port on the turret was removed. On March 19, 1943, the first Panzer IV with Schürzen skirts on its sides and turret was exhibited. The double hatch for the commander's cupola was replaced by a single round hatch from very late model Ausf. G. and the cupola was up-armored as well. In April 1943, the KwK 40 L/43 was replaced by the longer 75-millimetre (2.95 in) KwK 40 L/48 gun, with a redesigned multi-baffle muzzle brake with improved recoil efficiency.