Two units with the wheel arrangement Bo'2' were built in 1935 by Waggonfabrik Fuchs in Heidelberg and AEG. They were numbered elT 1998 (cream with red underside) and 1999 (dark green with yellow (lower) and grey (upper) window wrap).

ET 91 02 was destroyed on March 9, 1943, in a bomb attack on the Munich shunting yard. ET 91 01 survived World War II without major damage and was taken over by the Deutsche Bundesbahn From 1968 on, it was listed as Baureihe 491 in the DB numbering scheme, being assigned the number 491 001-4.

The train had been refurbished 5 times during its lifetime (1949, 1953, 1961, 1972, 1985), and suffered a number of changes to its livery. Between 1949-1953 it wore the Rheingold livery, that was grey underside, purple bodywork and cream wrap. Between 1953-1971 it had a black underside (standard underside paint still used today), maroon bodywork and custard window wrap. Between 1972-1985 this livery is changed to light blue bodywork and silver wrap. The last livery was applied from 1985-1995 (technically speaking it is still used today) and featured a marine dark bodywork and white window wrap.[1]

On December 12, 1995, the remaining unit suffered extensive damage in a frontal crash at Garmisch-Partenkirchen with 1044 235 of the Austrian Federal Railways and was subsequently taken out of service. The unit has been stationed at the Bahnpark Augsburg in Augsburg since May 2005.

The unit is currently being renovated, however, due to economical reasons it will not be put into a usable state again, the power bogie having been destroyed in the 1995 accident.