Diesel locomotive were classified as DET 1 and DET 2 (). Due to shortage of petrol products during World War I, they remained unused for regular service in Germany. In 1922, they were sold to Swiss Compagnie du Chemin de fer Régional du Val-de-Travers (), where they were used in regular service up to the electrification of the line in 1944. Afterwards, the company kept them in service as boosters till 1965. Fiat claims a first Italian diesel–electric locomotive built in 1922, but little detail is available. A Fiat-TIBB diesel–locomotive "A", of 440CV, is reported to have entered service on the Ferrovie
Electro-diesel locomotive take advantage of shorter sections of electrified main lines. Bombardier has built dual-mode variants of its AGC series for the French operator SNCF; the electricity is collected by means of a pantograph. In Russia, a number of electro-diesels were built which had both pantographs and diesel prime movers; these locomotives were actually multiple units, with distinct electric, diesel, and motor sections. These included: An experimental electro-diesel locomotive, DEL120, was built by London Underground in 1940 but was not a success. Two types have been built whose electricity source was a 750 V DC third rail. Electro-diesel locomotives and multiple units