The UIC-X coaches are the express train coaches of the German Federal Railways, which were put into service from 1952 and were in service there for up to 50 years. These coaches had a level of comfort that was unheard of in Europe until then. Until the early 1960s, they were called üm-coaches or m-coaches.

Our car was put into service as C4üm-54. After the European class reform in 1956, all upholstered classes were declared 1st class, the former 3rd class became 2nd class, and the coaches were redesignated accordingly (A for 1st class, B for 2nd class). Accordingly, the coach was reclassified as B4üm-54 (Bm232). The coach has 12 compartments with 6 seats each. The colour of the coach body for 2nd class was bottle green (RAL 6007) at this time.