TOO MANY CARS?

There are more than 500 million motor vehicles in the world today. In densely populated parts of the world such large numbers can cause problems. Traffic-related air pollution, traffic congestion and road safety are major issues in some countries.
There is no simple answer to congestion, but car manufacturers today spend a great deal of time trying to improve car safety and trying to reduce the amount of pollution that their engines produce.
Although most engines still use petrol or diesel, manufacturers are experimenting with alternatives such as hydrogen or compressed air. You can already buy electric cars that are cleaner and quieter than a normal car, but at the moment they are only practical for city driving.