There are now over 700 million motor vehicles in the world-and the number is rising by more than 40 million each year.The average distance driven by car users is growing too-from 8 km a day per person in western Europe in 1965 to 25 km a day in 1995. This dependence on motor vehicles has given rise to major problems,including environmental pollution, depletion of oil resources, traffic congestion and safety.