We are planning a trip in September. We will be landing in Frankfurt/M, then probably take a train to Rothenburg odT, then onto Munich to rent a car and visit Bavaria (all of the castles and Garmisch-Partenkirchen and so forth). We will be flying out of Munich. I understand that it is much less expensive to rent a car someplace other than a train station or airport. We will probably be staying at the 4 Points Hotel (Olympiapark) in Munich (on line U3, if I'm not mistaken?). I don't think we'll want the car once we get back to Munich. What would be a good place to rent a car which would be convenient both for getting from the HBF to the rental car place and from the rental car place to the 4 Points Hotel?