In 1971, the DB developed two prototypes of the 614 series. These diesel trains, designed especially for regional and regional traffica further development of the series 624 / 634were given a slightly tapered wagon body upwards, because a so-called "track-arc dependent wagon cabinet control system (GST)" was to be installed. This gave the train its typical shape. However, as the GST did nothing at the end of the day, the 40 series vehicles delivered between 1973 and 1977 were dispensed with this - but the housing shape remained.MAN produced the intermediate wagons for 25 units, while the wagon factory Uerdingen produced the railcars equipped with a 330 kW or later 367 kW engine. The last 15 fittings (from 1975) were then completely manufactured by MAN. Although the multiple trains were designed as 3-piece units (204 places in the second and 2 x 12 places in the first class), they were designed with multiple traction abilities andespecially in the initial periodwere occasion