Einheits-PKW (German for 'standard passenger cars') were supplied to the Wehrmacht between 1936 and 1943 in the three versions Leichter Einheits-PKW, Mittlerer Einheits-PKW and Schwerer Einheits-PKW (light, medium and heavy passenger car). These vehicles were supposed to replace the civilian vehicles previously procured by the Reichswehr with cross-country mobile vehicles that conformed with military requirements while simplifying logistics and maintenance by using standardized components. The program achieved neither of these goals.
Early on in the process of motorizing, first the Reichswehr and then the Wehrmacht had procured militarized versions of many different makes and models of civilian passenger cars. Therefore, the Wehrmacht's inventory of passenger cars was unsatisfactory in a number of respects when the open re-armament began in 1935. On the one hand, the existing vehicles' cross-country mobility and durability were not up to military requirements. On the other, their maintenance and parts supply were highly complex due to the large number of different makes, models, and often even model generations.
After the Nazi takeover of power, increased funding became available for mechanization, and in 1934, a development program for standardized chassis was launched. It strove to achieve maximum cross-country mobility and extensive standardization of parts while employing the latest innovations in automotive engineering so the vehicles could be produced over a long period of time without many changes. Five types were initially planned:
Among other features, all types were required to have four-wheel drive, have independent suspension, and use domestic raw materials as stipulated by the Four Year Plan. However, due to the limitations of the German automotive industry at the time, the desired standardization was compromised right from the start. No single manufacturer was able to supply the required number of cars on its own. Several manufacturers were therefore charged with production, each supposedly following the same standardized plans: BMW (Werk Eisenach), Hanomag, Stoewer, Opel (Werk Brandenburg), Ford Germany and Auto Union (Horch and Wanderer). However, these companies in turn outsourced production of a large fraction of the individual components to different third-party suppliers. Also, each used engines from its own line-up of civilian models, so engines were not standardized from the outset.