This paper describes a new dynamic model which integrates the effects of expected demographic and economic developments on the growth of car ownership. The model known as the COHORT PROCESSING MODEL is based on the evidence which emerged from the analysis of data from the past, that better and more comprehensible modelling is possible for long term development of car ownership within separate birth year cohorts of men and women than for the growth of car ownership by taking the population as a whole. The reason for this is that a large part of the overall long term growth in the number of cars is due to the population turnover in the course of time, because of the fact that the penetration possibility of car ownership within a population and gender cohort is heavily linked with birth year of that cohort. Younger generations are more likely to own cars (which means a higher potential for car ownership growth) than older generations. This is because younger generations are more likely to have a car licence, and more inclined to own a car, and have on average higher salaries. Especially with women there are large differences between successive cohorts in these respects. The highly disaggregated COHORT PROCESSING MODEL can take into account this constantly changing composition of the population due to the flow of the qualitatively differing cohorts through time. Disaggregated forecasts of demographic developments are linked with (disaggregated) scenario's for economic growth, using equations and parameters which have been estimated by analyzing for the period 1975-1985 within separate cohorts the relationship of developments of car ownership penetration, drivers license holding penetration and growth of income. In the paper both the model and the forecast results for the possible growth of the passenger car park in the Netherlands up to 2010 will be presented. It will show that when economic growth is favourable the number of passenger car can grow to 8 million cars in 2010.
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