I'm off to Norway this spring for a week and a half. Don't know whether a rental car is a good idea or is the public transportation pretty good for sightseers. Does one need an International driver's license?
My DH had an international driver's license when we went to Norway. But, the trains are excellent and most towns have great public transportation. We did get a car since I was sightseeing, and he was working at one of their naval bases, teaching a class. He also got off work extremly late and the public trans wouldn't run that late. We went to Bergen and Oslo. In Bergen, most everything was in walking distance. In Oslo, the busses were great.
I spent a week in Oslo last winter. As it was winter, there weren't many sights to see because it was so dark and everything closed really early, but the busses and trains seemed to be very convenient and cabs were plentiful. Oslo is a nice walking city. I'm sure it will be just beautiful in the spring.