In Bavaria, the electrification of rail lines was already beginning before World War I. When the network radiating from Munich was put under catenary starting in 1925, the German State Railroad looked for suburban powered rail cars available at short notice. Initially, four steam-powered rail cars of the Bavarian class MCCi were converted to electric powered rail cars. These prototype units were later designated as road numbers ET 85 01-04 and turned out so well that another 32 units in an improved version were placed into service between 1927 and 1932. In addition came 34 control cars and 70 trailer cars converted from old passenger cars.
In 1950, the German Federal Railroad (DB) still had 21 of the class ET 85 on its roster and reliably underway in the greater Munich area in the typical red DB powered rail car paint scheme. In the Sixties, the star for the class ET/ES 85 trains in Munich began to sink. Several sets went into commuter service in the Koblenz and Regensburg areas as well as to Freiburg, which used these quaint units on the Three Lakes line in the Black Forest.
All the still existing power and control cars were given computer-generated numbers (class 485/885) except for road number ET 85 21, the prototype of the Märklin model, and road number ET 85 24. The last sets spent their time in their old hometown at the start of the Seventies in factory service from Krauss-Maffei and to the maintenance facilities in Freimann and Neuaubing.
The history of old Bavaria finally ended in Baden, where road numbers 485 005 and 485 019 were retired on September 28, 1977. The set 485 007/885 615 remains preserved and on display at the SVG Railroad Adventure World in Horb on the Neckar, as well as road number 885 706 as an association residence in Freiburg.