We just got back from Germany last Friday. We were there through the holidays and visited France, Switzerland, and Italy by car. What I did was go to the vodafone store in the stuttgart train station and got a local phone company (Lebara) sim card. There were options from 25-35 euros for 30 days of service. With a sim card you get the advantage of being able to communicate as well as navigate. I then used the waze app for navigation. I have found that waze is better than google maps. We used it last spring in Costa Rica as well, and it has worked flawlessly. Your phone has to be a GSM phone for this to work, and possibly unlocked.