The Sturmwagen looks like a surprisingly advanced vehicle for 1918. A dedicated assault gun. Now we know where the WW2 Sturmgeschutz came from!
A similar question has been asked about the Ehrhardt on the armoured car forum. The Ehrhardt, Mgebrov and Duhrkopp were clearly real vehicles. Was the Duhrkopp perhaps a competitor to, or prototype for, the Uberlandwagen? I believe that several designs of "Russo-Balt" cars were built.
"A dedicated assault gun." it was intended to be armed with a machine gun
"Was the Duhrkopp perhaps a competitor to, or prototype for, the Uberlandwagen?" they seem to be different, the A7V Uberlandwagen (supply carrier) was constructed in 1917 together with the A7V Sturmpanzerwagen and the Duhrkopp Wagen was constructed in 1916 starting as a tank and ending as a supply carrier