I have a question about Lufthansa's Rail and Fly. Is it possible to take a German trains (e.g. ICEs) from an airport in Germany say Frankfurt to outside of Germany say Zürich?
No you cannot except Basel (CH). The regulations state:
- to/from each of the more than 5,600 DB railway stations.
- to/from any German airport and Basel Airport on the entire DB rail network.
Rail & Fly is meant for travelers that depart from or return to Germany or Basel. The train has to go to or from those destinations, either on the day of the trip or the day before.
You cannot use this kind of ticket all the way down from Frankfurt to Zurich. However, it is possible to combine the Rail & Fly with a regular ticket. In your case you can buy a Rail & Fly from Frankfurt Airport to the German railway station in Basel (Basel Badischer Bahnhof) and then a regular ticket to Zurich. You can stay inside the same train with your two tickets. The station "Basel Badischer Bahnhof" belongs to Germany and hence the Rail and Fly is valid there.
The full (flexible) fare for Frankfurt-Zurich is 106 EUR in the 2nd class. The Rail & Fly is 29 EUR and the standard ticket from Basel Badischer Bahnhof to Zurich is 28 EUR. This combination will save you 49 EUR each way.