Berlin, though, has become the largest one-way, car-sharing city in the world. One-way or free-floating services, which recently started in the United States, use GPS and smartphone apps for far more flexible car sharing. Cars are parked on city streets, and users pick up cars parked nearest to them. Instead of bringing the car back to a lot, users leave it wherever they find parking near their destination.

These new systems have been making an impression. Since the first commercial one-way car-sharing systems started in Germany two years ago, 183,000 people have signed up, according to Bundesverband CarSharing — a large number, considering that long-established car-sharing systems in Germany have 262,000 members.

Photo Credit: A Car2Go smart car parked in England. Elliott Brown / Flickr