The car companies are waiting for another oil crisis when consumers will demand improved fuel efficiency. There have, however, been some technical improvements. Lead emissions in the US dropped by 94 per cent in the ten years after lead-free gasoline was introduced. And carbon monoxide emissions fell by half in Japan during the 1970s. Improvements in Third World countries have been slower, since their car models tend to be based on old Western technology.
Maintenance is also more irregular and enforcement more difficult.
Mexico, with one of the Third World s biggest car fleets, has almost no emission controls. Individual cars are polluting less, but the sheer volume of cars has meant overall pollution may be increasing. Between 1976 and 1985 the total number of miles driven increased by 50 percent. The global auto fleet burns billions of litres of non-renewable petroleum and uses massive quantities of raw materials. In 1985, motor vehicles burned 44 per cent of all the petroleum used in Western Europe and 49 per cent in the Third World.