- This paper critically analyses the voluntary agreement of the European Automobile Manufacturers Association (ACEA) which is intended to ensure a significant reduction of average CO2 emissions from new passenger cars. It concludes that the voluntary agreement is far from being an adequate solution in terms of both ecological effectiveness and economic cost-efficiency. Therefore, the paper proposes to replace the voluntary agreement by an emission trading scheme which directly places car makers under obligation. This switch in policy should be accompanied by further phased increases in the ecotax levied on fuels and a vehicle taxation system that places greater focus on CO2 emission.