Distributional and Environmental Effects of an Emissions-Differentiated Car Sales Tax

European countries introduced a combination of demand-side fiscal policies and mandatory supply-side emissions standards to reduce CO2 emissions rates of new cars. I quantify the equilibrium response to one of the most drastic demand-side policies, the Finnish CO2 differentiation of automobile sales tax rates. Despite having a drastic market impact, this environmental tax reform did not drive the observed decline of new-car CO2 emissions rates, given the concurrent introduction of mandatory EUCO2 emissions standards for manufacturers. The CO2 tax-rate differentiation however led to increased local pollution by promoting the sale of diesel-powered cars. The tax reform had a positive net welfare effect as it lowered tax rates on average. It was nonetheless also a regressive policy with large tax revenue losses and a disproportional benefit to high-income consumers. Optimal fiscal policy aiming to balance environmental and public finance goals needs to consider both the market structure as well as other concurrent policies on different levels of government.