U-Bahn's opening in 1902, 42 multiple units and 21 pure railroad cars were ready for service. Unlike the test vehicles, the seating was placed along the walls of the train, which was considered more comfortable. This arrangement is still used today. These trains had a top speed of . Between 1906 and 1913, a fifth batch of vehicles was delivered; these had an improved steering system, making possible 8-car trains, which had become necessary due to rising traffic. Originally there were smoking compartments and third class cars on the U-Bahn. Different classes were abandoned in 1927. In 1926 the Schöneberg U-Bahn, which had been independent and had used their own vehicles up to that point, were taken over by the main U-Bahn network. Because a connection to the rest of the network had been planned from the beginning, the Schöneberg trains had been built to the same specifications as the main network. From 1928 to 1929 a new type of Kleinprofil was introduced, the A-II cars. The most notable difference to the A-I type was that the A-II only had three windows and two sliding doors. Berliners called these trains Ammanullah-cars because the Afghan king Amanullah Khan had supposedly steered one of these trains during his 1928 Berlin visit. A3 type cars After World War II a new batch of vehicles became necessary - the trains had been badly damaged in the war. At this point the new A3 type, modelled on its big Großprofil brother DL, was designed. There were three batches of this type in the years 1960/61, 1964 and 1966. However, because these were built from steel, the new trains required a large amount of electricity. A3 trains have begun refurbishment for A3-64 and A3-66 from 2003 to 2006, known as A3E, but 8 trains were scrapped in 2000. Based on the A3, the A3L type built from aluminum was developed. G type cars 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 GI double multiple unit, called Gustav in popular parlance. As before, the seats were located alongside the train walls. The top speed was . The smallest unit of these trains were half trains made up of two double multiple units. After intensive testing the LEW