In the first years after World War II, the development of promising designs, chiefly in the diesel sector, formed an urgent task for the newly established German Federal Railroad. The DB therefore decided to use the DRG VT 872 and 874 powered rail cars, which were no longer operational, as test vehicles. These heavy, four-axle, diesel-electric units were purchased in 1932 for shuttle service between Frankfurt and Wiesbaden. They marked the end of powered rail cars derived from heavy, riveted passenger cars, but the application of the 410 horsepower Maybach motor for the first time was in turn the beginning of diesel-powered rail cars in main line use. This motor in an improved form was subsequently one of the mostly widely used on the DRG in express as well as regional powered rail cars.
In 1949, MAN was therefore given a contract to convert the two powered rail cars for new propulsion equipment. New road numbers were provided, VT 92 501 (former VT 872) and VT 92 502 (former VT 874). Actually, only road number VT 872 was converted. Its old motor was removed and replaced by the new standard design mechanical equipment from MAN, Maybach, or Daimler-Benz. The electrical drive was abandoned and replaced by hydraulic drives from Maybach or Voith. The interior was not the only thing that was transformed. An external metamorphosis was also done. The unit was given a totally new superstructure with a streamlined shape ("Egghead") and it thereby became the prototype for all powered railcars of the first new construction program for the DB (ET 30/56, ETA 176, VT 08/12). In addition, road number VT 92 501 also made an important contribution to the development of the V 200 large diesel locomotive. The first paint scheme for road number VT 92 501 had an orange/brown window band and beneath it a reddish brown paint job, which resulted in the nickname "Potato Beetle".
After completion of the experiments, road number VT 92 501 was given a standard crimson paint scheme. Starting in 1956, it was based at Nürnberg Main Station and ran as a "locomotive" pulling limited stop fast trains and passenger trains to Amberg, Bayreuth, and Furth im Wald, since a passenger area was no longer present in it. In the early Sixties, it was assigned to the Nürnberg maintenance facility as a towing unit to transfer damaged diesel-powered units as well as trailer cars and cab control cars or units due for regular maintenance. In 1978, the maintenance deadlines came due for this powered rail car designated as road number 692 501 since 1968. Since there was no compelling reason to maintain it anymore, this powered rail car was retired on December 21, 1978.