The class E 10 is an electric locomotive of the Deutsche Bundesbahn, introduced in 1952. It belongs to the Einheits-Elektrolokomotiven (standardised electric locomotives) program and was built for express passenger service. In 1968 the series was redesignated as class 110 (E10) and class 112 (E10.12). In 1988 the last series of class 112 locomotives were designated as class 114, and in 1991 the remaining locomotives of class 112 were designated as class 113. In 2006 38 locomotives were designated as class 115. these trains will run both RE and freight services across the route they will run 64 re services and 41 freight services with this add on it would really bring to life germany from the 1950's
The 110 also runs with n-Wagen on RRO and my Köln-Wuppertal suggestion to this day under the National Express brand. All in all seeing older German locos would be fun, with the BR 151 and BR 111 also being high up my list. A '70s (or '80s/'90s) route with the BR 103 and many other loco's could be a different option, which also sounds really fun to me.
