Well that depends on where you plan to wander. Downtown Friedrichshafen, about 2 miles from Friedrichshafen Airport (FDH-Friedrichshafen - Lake Constance), can be tricky to drive in. Make it easy on yourself by renting something small, fuel-efficient, and simple to operate. That being said, Friedrichshafen is also a jumping off point for some of the caves in Bodenseekreis. If your escape is more about hitting the wide open road, then you may like something with a little more comfort and room to move around. How about an SUV or a full-size car?