The Schwerer Panzerspaehwagen (7.5 cm Pak 40) was a result of a meeting with Hitler in October of 1944.
Hitler ordered the development of the Pak 40 on the 8-Radwagen to be accelerated so that, if possible, the new armament could be mounted during the December production run.
During a Conference on 28/29 November 1944, Hitler again emphasized that he laid decisive value on the immediate start of series production of the Pak 40 on the 3-ton SPW and the 8-Rad-SPW.
Then on 5 December 1944, after having viewed the demonstration of new weapons and equipment, Hitler called the Panzer-Grenadierwagen with the Pak 40 and the 8-Radwagen with the Pak 40 one of the best technical solutions of this war.

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The Sd.Kfz.234/4 was a final attempt to provide troops with mobile anti-tank gun in an attempt to improve the desperate war Situation in December of 1944.
Sd.Kfz.234/4 was based on Sd.Kfz.234/3 with modified superstructure and armed with 75mm Pak 40 L/46 anti-tank gun with limited traverse and elevation.
Only 36 rounds of ammunition were stored inside along with single 9mm MP was provided for crew defence.
The vehicle was heavier than its predecessors.
Production of the vehicle unofficially nicknamed Pak- or Kanonen-Wagen started in December of 1944 and some 90 were produced by Buessing-NAG until April of 1945.
New vehicles were mostly issued as replacements to new and refitted units including 1st Division of Russian Liberation Army (ROA), which used them during their operations in and around Prague in May of 1945.