The PzKpfw III Ausf E was the last of the pre-production series.
These were still on troop trial on September 1, 1939. A few had the 50 mm L/42 gun installed with covers on air intakes.
Early models had the pre-production turrets that had two machine guns coaxially. New improvements were a two part visor for the driver, and the single door in the side of the turret was replaced by a double door with vision slots and pistol ports.
The suspension was redesigned with six independent bogie road wheels, suspended from torsion bars. New suspension with individually supported road wheels.
Had a new transmission and more powerful engine. The transmission was rather complicated but it was intended to make gear changing easier. The 9th and 10th gears were overdrive.