The cars are modified Renault Zoe and Mitsubishi i-MiEV electrics and have a driver in front who is prepared to take back the wheel and a researcher in back who watches the car’s computers. For now, the taxis only run in a 2.5-square-mile (6.5 square kilometer) business and residential district called “one-north,” and pick-ups and drop-offs are limited to specified locations. To take a ride people must have an invitation from nuTonomy. The list will be expanded to thousands to offer this experience to as many people they can even in this experimental stage of the project. The ultimate goal is to have a fully self-driving taxi fleet in Singapore by 2018, to help cut the number of cars on Singapore’s congested roads. They think autonomous taxis could ultimately reduce the number of cars on Singapore’s roads from 900,000 to 300,000.