A private car used to be a luxury for most Chinese. Now it can be seen everywhere in China. Cars have become an indispensable part of people\'s life. People not only drive to commute to and from work but also take self-driving tours frequently. In some cities, the number of private cars is growing so fast that such problems as traffic congestion and parking lots deficiency have become increasingly serious. The municipal governments of these cities have to introduce new rules to limit the number of cars on roads. Considering the worsening condition of air pollution, a growing number of people choose to buy new-energy vehicles at present. Simultaneously, Chinese government has also taken some measures to support the development of new-energy vehicles.