In the course of the First World War and the realization that the German troops urgently needed armored vehicles, the War Department commissioned various companies in the Reich to develop these vehicles.
Among other things, the prototypes of the Dür car and the Treffas car were created from this invitation.
The Dür car was a prototype of the Dürkoppwerke from Bielefeld, which began in mid-1916 with the development of an armored and all-terrain vehicle. The model presented by the company, whose prototype was limited to the chassis, was equipped with a pair of crawler tracks, each powered by an 80hp engine. However, the chassis proved to be too weak to accommodate an armored body. So the 10 already built racks were converted into vans and the project was discontinued.
Also the company Hansa-Lloyd from Bremen presented to 1 February 1917 a prototype of an armored vehicle before the war Ministry. However, this Treffas car also could not convince the Ministry, especially since at this time the decision for the production of the A7V had already fallen.
You can find the right literature here:
Armored Vehicles of the German Army 1905-1945 (Spielberger German Armor and Military Vehicle)
This classic, definitive series continues with this volume on German armored vehicles from 1905-1945. Spielberger, a leading expert in the field of German military vehicles, presents the wide variety of four-, six-, and eight-wheeled types and their wide range of uses in this richly illustrated technical documentation. Types include the WWII era Sd.Kfz.231, Sd.Kfz.222, Sd.Kfz.232, and many others from a wide variety of manufacturers.
German Panzers 1914–18 (New Vanguard)
Panzer warfare is synonymous with the Wehrmacht of World War II. This book examines the story of the Panzer's more mysterious ancestors, the little-known panzers of the Great War. Germany was very slow to develop armored vehicles compared to Britain and France. Early attempts such as the Marienwagen of 1915 were technical failures, discouraging further design efforts until the utility of the tank was proven by the British and French in 1916-17. Efforts to catch-up proved difficult, and only a couple dozen German A7V tanks were completed in time to take part in the final campaigns of 1918. As a result, the majority of German panzer units actually used captured British tanks, the Beutepanzer. This book will trace the development of German panzers of the Great War, including the A7V and its intended but unfinished stablemates. Also included will be an overview of the use of panzers by the German Army in World War I including both A7V and Beutepanzer units.
The German A7V Tank and the Captured British Mark IV Tanks of World War I (A Foulis military book)
, 240 pages illustrated with over 25 black ans white photographs and line drawings, SIGNED by both Maxwell Hundleby and Rainer Strasheim on a label stuck down to the front pastedown
German Tanks in World War I: The A7V and Early Tank Development (Schiffer military history)
This book covers the earliest forms of German armored fighting vehicles used primarily in WWI.