Abstract
It is often suggested that a rise in car use will be beneficial for the national economy. This statement however is not valid under all circumstances. Like other economic activities, road traffic is subject to the law of the diminishing returns. A higher level of transport corresponds with lower marginal benefits. If these marginal benefits are less than the additional social costs, the supposed rise in car use will be unprofitable for the national economy. Considering the social costs of road traffic it is indicated that the current level of car use is at least 25% higher than the economic optimum. (A)