This paper investigates whether the vehicle taxation system in Belgium is stimulating the demand of clean vehicle technologies. A life cycle cost analysis will be performed to evaluate the cost-efficiency of several vehicle technologies within the current fiscal system. This life cycle cost will be weighted against the environmental performance of each vehicle to discover the market potential of environmental friendly vehicles and to define necessary fiscal regulations. Additionally, the yearly taxes and external costs (environmental, congestion, accident costs) of each vehicle will be compared, identifying the strenghts and distortions of the Belgian fiscal system with respect to the promotion of clean vehicles. Moreover, it will be examined whether a new vehicle taxation system, based on the environmental performance of vehicles, would be effective in tackling the current distortions while keeping the good incentives for stimulating the demand of clean vehicle technologies. This new vehicle taxation system will be based on a environmental rating tool, the so-called Ecoscore. The Ecoscore enables a comparison of the environmental burden caused by vehicles with different drive trains and using different fuels and is in this respect a very appropriate instrument to introduce a technology neutral reform of the fiscal system. By calculating the tax burden of several vehicles within the current and new fiscal system, it will be assessed whether this new fiscal system is able to evoke a shift in the composition of the vehicle fleet towards a more environmental friendly one.