The emission of pollutants and energy use of the car fleet is strongly affected by the age composition of the fleet, since catalytic converter technology and fuel efficiency have been developing rapidly. Consequently, for forecasting emissions and fuel consumption, the rate at which cars are scrapped is an important determinant. The present UK vehicle market model, developed by the University of Leeds and Napier University, contains a vehicle survival model, which is used to predict how many and what type and age of cars will be scrapped. It can thus provide information about emissions and energy use in addition to forecasts of fleet size. However, the basic assumptions of this survival function have not been tested against behavioural data. Many factors might be influencing scrappage decisions, including the occurrence of accidents, vehicle deterioration, repair cost, the supply and price of replacing vehicles, changes in physical incapacity of drivers, income, household composition, and expectations about the cost of vehicle ownership and operation. Only limited knowledge exists on the relative importance of these factors. In a project for the UK Department of the Environment, Transport and the Regions (DETR), carried out by the Institute for Transport Studies of the University of Leeds and Hague Consulting Group (now RAND Europe), the existing literature on vehicle scrappage models has been reviewed. The main outcomes of this review are presented in this paper.
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