The Impact of New Passenger Vehicle Changes and the Shift to Diesel on the European Union’s NewAutomobile CO2 Emissions Intensity

摘要

This paper identifies trends in new gasoline and diesel passenger car characteristics in theEuropean Union between 1995 and 2009. By 2009 diesels had captured over 55% of the newvehicle market. While the diesel version of a given car may have as much as 35% lower fueluse/km and almost 20% lower CO2 emissions, diesel buyers shifted to increasingly larger andmore powerful cars more than the gasoline market. As a result, new diesels bought in 2009 hadonly 2% lower emissions relative to gasoline cars, an "advantage smaller than that of 1995. ALaspeyres decomposition investigates which factors were important contributors to the observedemission reductions and which factors offset savings in other arenas. More than 95% of thereduction in emissions per km from new vehicles arose because both diesel and gasoline newvehicle emissions/km fell, and only 5% arose directly because of the shift to diesel technology.Increases in vehicle weight and power for both gasoline and diesel absorbed much of thetechnological efficiency improvements offered by both technologies. We also analyze theimplications of the uncertain diesel black carbon soot as a factor offsetting the CO2 advantage ofdiesel cars. Finally, we observe changes in the gasoline and diesel fleets in eight EU countriesand find changes in fuel and emissions intensities consistent with the changes in new vehiclesreported. While diesel cars continue to be driven far farther than gasoline cars, we attribute onlysome of this difference to a “rebound effect”. We conclude that while diesel technology haspermitted significant fuel savings, the switch from gasoline to diesel in the new vehicle marketcontributed little itself to the observed reductions in CO2 emissions from new vehicles.