Why has car-fleet specific fuel consumption not shown any decrease since 1990? Quantitative analysis of Dutch passenger car-fleet specific fuel consumption

The Dutch car-fleet specific fuel consumption has not shown any decrease since 1990. The main reasons for the car-fleet specific fuel consumption no longer showing a decrease after 1990, namely, increases in vehicle weight and cylinder capacity, have been concluded from an analysis of Dutch car-fleet specific fuel consumption in the period 1980–1997. The increase in weight of the average sales-weighted new car in this period can be almost completely explained by the increase in weight of successive models (upgrading). This upgrading is partly the result of competition between car manufacturers but is also due to stricter safety requirements. However, because upgrading has been fairly extreme, the 1981 model of a car type often belonged to a different car type than the 1997 model of the same type. Upgrading is therefore a consequence, not only of the competition among car manufacturers and stricter safety requirements, but probably also of the shift in consumer demand for more expensive, larger and heavier cars. The 1998 agreement with the European car manufacturers (ACEA) and the Dutch CO2 differentiation in car purchase taxes will probably lead to a further decrease in specific fuel consumption in the European fuel test-cycle (Eurotest) in the near future. However, real-world specific fuel consumption will decrease less because the difference between specific fuel consumption measured in the Eurotest and real-world specific fuel consumption is expected to increase as a result of the increasing use of both air conditioners and direct-injection gasoline engines.