Also a few years ago, but I rented a car and drove all over Germany, Austria, and other countries without a GPS and without problems. Even got my Peugeot station wagon up to 110 MPH on the autobahn once, just to say I did. That was too fast for me though. Watch out around some of the little towns. We did run across some roads that were quite narrow; in some cases only wide enough for one vehicle at a time. When you met someone, one of you had to pull off as far as possible to let the other pass.

Have fun, I enjoyed our time there.