As big cars cause many problems, such as pollution, shortage of parking space, crowded traffic, scientists are now trying to design some small cars that may some day replace today's big automobiles. If more people begin to drive such cars in the future, there will be less air pollution. There will also be more space for parking cars in cities, and the streets will be less crowded. Three such cars can fit in the space that is now needed for one car of the usual size. The little cars will cost much less to own and to drive. Driving will be safer as these cars can go only 60 kilometers per hour. The cars of the future will be fine for driving around the city. However, they will not be suitable for long trips, because these cars by petrol can only go 450 kilometers before needing to stop for refilling.