The Sturmgeschütz was conceived as a support gun for infantry, which could advance along with the infantry, to help fight down strongpoints and enemy tanks. They were also intended for indirect fire for defensive operations. This was a supplement to the light infantry guns and anti-tank guns the infantry already brought with them, but they were considered as a possible replacement to the anti-tank guns.
They were not intended to operate independantly in large groups, but rather along the infantry at platoon level.
After Germany encountered the Russian heavy tanks, it was decided that the gun and armour should be upgraded to allow the Sturmgeschütze to fight these tanks as well. This was not an abandonment of the original Sturmgeschütz role - it was always intended to fight tanks, the upgrade was merely a necessity for them to continue to have any significant firepower against the tanks most likely to be encountered.
Later in the war, as the Panzer production struggled to keep up with demand, Sturmgeschütze were pressed into service as Panzerjäger. This was still not an abandonment of the original role. The Sturmgeschütze in the Panzerjäger role were used as such, but the Sturmgeschütze were still used in their original role too. In the Sturmgeschütz role, they were to fight along with the infantry, and should not fight alone or as tanks. They were obviously still used for defensive duties, which would include basic Panzerjäger duties such as ambushing tanks, but this had always been a part of the Sturmgeschütz role.
|Month||Sturmgeschütz Ausf.A to Ausf.E||Sturmgeschütz Ausf.F to Ausf.G|
|Sturmgeschütz Ausf.A||Sturmgeschütz Ausf.C-E||Sturmgeschütz Ausf.F and F/8||Sturmgeschütz Ausf.G|
|Length||5.38 m.||5.40 m.||6.31 m.||6.14 m.|
|Length (without gun)||5.38 m.||5.40 m.||5.30 m.|
|Width||2.92 m.||2.95 m.|
|Height||1.95 m.||2.15 m.||2.16 m.|
|Firing height||1.5 m.||1.55 m.||1.60 m.|
|Weight||20.7 t.||22 t.||23.2 t.||23.9 t.|
|Engine||Maybach HL 120 TRM 12 cylinder water cooled 11.9 l. gasoline|
|Horse powers||265 @ 2,600 rpm|
|Armour||10-50 mm.||10-80 mm.|
|Main gun||7,5 cm Kan L/24||7,5 cm StuK40|
|Secondary gun||2 * 9 mm M.P.||
|Maximum speed||40 km./h.|
|Road speed||20 km./h.|
|Cross country speed||12-15 km./h.|
|Range (on road)||160 km.||140 km.||155 km.|
|Range (cross country)||85 km.||95 km.|
|Fuel capacity||310 l.|
|Fuel usage (on road)||1.93 l./km.||2.21 l./km.||2 l./km.|
|Fuel usage (cross-country)||3.1 l./km.||3.65 l./km.||3.26 l./km.|
|Fording||1 m.||0.80 m.|
|Step climbing||0.60 m.|
|Trench crossing||2.3 m.|
|Ground pressure||0.95 kg./cm2||0.96 kg./cm2||1.01 kg./cm2||1.04 kg./cm2|