An kara yawan sabis a cikin motoci 5 a shekarar 1918, kuma Metropolitan ya gabatar da sabon kaya a shekarar 1921.
Tabbas, sigar da ta fi rikitarwa ta jumla ita ce "An haɓaka sabis a cikin motoci 5 a cikin 1918, kuma a cikin 1926 Metropolitan ya karɓi duk layin Circle da ke aiki ban da jiragen ƙasa 3 a ranakun Lahadi. "