Class G are a type of electric multiple unit trains used by Berlin U-Bahn.
While in West Berlin newer and newer vehicles were built and used, in East Berlin the pre-war A-I and A-II trains were still running. Finally, in 1975 the Thälmannplatz — Pankow route got four prototypes of the new G double multiple unit, called Gustav in popular parlance. As before, the seats were located alongside the train walls. The top speed was 70 km/h. The smallest unit of these trains were half trains made up of two double multiple units. After intensive testing the LEW Hennigsdorf factory began manufacturing the trains. The production models had lower side windows and a changed front, but were technically the same. 114 cars were built until 1982. There were 24 more, but those were delivered to Greece for a railway line there. They were returned to Berlin in 1984/85.
In 1987 a new batch of GI-trains was delivered, but with technical changes that made coupling them with the older cars impossible. Because of these changes the new trains were called GI/1. Their popular nickname was Gisela. A speciality of these cars was the fact that they had only two doors per side, unlike the other Kleinprofil trains, which had three.
Most of the trains were deployed to the former eastern part of U2, before reusing it on U1 (Schlesches Tor - Ruhleben) for the increasing night service in December 1990, before deploying it on U12 and U15 in 1993. As of today, this trains are deployed on U1 and U2. Those trains are not deployed on U3 and U4 unless it is for emergency use. Trains were renumbered to use 2xx - 4xx numbers in 1992.
All the older G stock were sold to Pyongyang (GI), the G cars went for scrap in 1997, and all the GI/1 trains were refurbished into GI/1E from 2005 to 2007 in order to extend the lifespan.