The impact of ‘Cash for Clunkers’ on greenhouse gas emissions: a life cycle perspective

Abstract

One of the goals of the US Consumer Assistance to Recycle and Save (CARS) Act of 2009,more commonly known as ‘Cash for Clunkers’, was to improve the US vehicle fleet fuelefficiency. Previous studies of the program’s environmental impact have focused mainly onthe effect of improved fuel economy, and the resulting reductions in fuel use and emissionsduring the vehicle use phase. We propose and apply a method for analyzing the net effectof CARS on greenhouse gas emissions from a full vehicle life cycle perspective,including the impact of premature production and retirement of vehicles. Wefind that CARS had a one-time effect of preventing 4.4 million metric tons ofCO2-equivalent emissions, about 0.4% of US annual light-duty vehicle emissions. Of these,3.7 million metric tons are avoided during the period of the expected remaining life of theinefficient ‘clunkers’. 1.5 million metric tons are avoided as consumers purchase vehicles thatare more efficient than their next replacement vehicle would otherwise have been. Anadditional 0.8 million metric tons are emitted as a result of premature manufacturing anddisposal of vehicles. These results are sensitive to the remaining lifetime of the ‘clunkers’and to the fuel economy of new vehicles in the absence of CARS, suggestingimportant considerations for policymakers deliberating on the use of acceleratedvehicle retirement programs as a part of the greenhouse gas emissions policy.