A fleet of modified Toyota Prius cars was driven more than 200,000 kms with only one accident, and that one was when a car was being human-driven. To start, the driver sets a destination, the car calculates the route and begins to drive on its own. It uses Google Maps to anticipate traffic lights, stop signs and other landmarks. It follows posted speed limits. Then the human "driver" can step in to take control if need be.