The first electronic car was invented in 1981. Although it shocked the world, its performance was not as good as cars using oil. But after the fuel crisis and the problem of pollution has been recognized, people put their eyes back on the environment-friendly cars. The first thing we should revolute is the fuel. In order to reduce the air pollution, oil should be changed to battery or use low oil-using engines. But the capability of battery is still not big enough. So there is a long way for environment-friendly cars to go...