Württemberg was the only state railway in Germany in the first two decades since the beginning of railway construction to base its designs on the "American system". Only 4-axle passenger coaches with a central corridor and open platforms for entry were acquired, including 181 3rd class carriages, which were built in three series between 1845 and 1867. Modified several times, equipped with toilets and different windows, many of them were in service for more than 70 years. In 1907 they were assigned to the newly created 4th class and added to the stock of the DRG as Di, where they remained in regular service until the 1930s.
