Initially 1,750 were ordered, and of those 10 chassis were used for Hummel prototypes and 53 chassis for Brummbär. Dropped vision ports from turret sides. New cupola with thicker armor and single hatch cover. In the summer of 1942 a new muzzle brake with a double baffle and a system to allow transfer of coolant to aid in cold weather starting was installed (Kühlwasser-Austauscher). In January 1943 the driver's scope was eliminated. In 1943 Schürzen we installed to the side of the hull and the turret. Late production PzKpfw IV Ausf Gs had new drive sprocket and radio antenna was moved to left hull rear. 75 mm gun had double baffle muzzle brake. Starting on June 20, 1942, extra armor was bolted or welded on to approximately 700. 1,275 received the 7.5 cm KwK 40 L/43.
From late 1942 / March 1943the 7.5 cm KwK 40 L/48 was installed. Had a velocity of 751 m/s / 2,461 ft/sec.
Schürzen (skirting) armor was added to help stop Russian 14.5 mm AP rounds.