Under the designation ET 56, the Bundesbahn procured a total of seven three-car multiple units in the 1950s, which were intended for fast local transport. They each consisted of two motor cars and a trailer, which was designated EM 56. From 1968 the motor cars were given the computer numbers 4561 and 4564, while the trailers became the class 846.
A special feature of these vehicles, which were created in the post-war period, was that their technology still came from pre-war railcars, but the exterior was adapted to newly developed locomotives and railcars. The transformers and nose-supended traction motors of some type ET 25, ET 31/32 and ET 55 motor cars were used, which were in the inventory of the Bundesbahn with external war damage.
Since the entire equipment was already installed under the floor, they formed a good basis for modern railcars. The outer bogie of the motor car was driven on both axles and with the gear ratio of the former ET 55 90 km/h was reached. The car bodies in modern design were constructed as load-bearing tubes, which ensured a clean external appearance. The lower part formed skirts in which the aggregates were housed. There was a capacity of 262 seats per train and for expansion, several multiple units could be coupled together and driven in multiple traction.
The first area of application was the Stuttgart area, where they ran until 1970. They then came to Heidelberg, where the gear ratio was changed for a top speed of 110 km/h. The decommissioning lasted until 1986 and today none of the seven trains are left.