题目：What Does an Electric Vehicle Replace?（Authors: Jianwei Xing， Benjamin Leard， Shanjun Li）
摘要：The environmental benefits from the adoption of electric vehicles (EVs) critically hinge on the types of vehicles EVs replace: the smaller the difference in emissions between EVs and the vehicles that would have been bought had EVs been unavailable, the lower the emissions reduction from EV diffusion. Estimating the emissions consequences from EV incentives therefore depends on how consumers substitute between vehicles of different fuel types and emission ratings. Using a random-coefficient discrete choice model, we estimate these substitution patterns by combining detailed micro and macro data on new automobile purchases between 2010-2014, a period of rapid growth of EV sales. With our estimates, we show which types of vehicles that EVs replace, and we estimate how these substitution patterns translate into reduction of emissions from various incentives for EVs. Our results suggest that the vehicles that EVs replace are relatively fuel-efficient: 79 percent of EVs replace gasoline vehicles with an average fuel economy of 27.2 mpg, which is 3.5 mpg higher than the average fuel economy of gasoline cars, and 12 percent of them replace hybrid vehicles. In 2014, the federal income tax credits lead to a 29 percent increase in EV sales and resulting environmental benefits of $73.8 million (or 10 percent of the total subsidy), which could have been larger had EVs replaced more fuel-inefficient vehicles. We also find that alternative subsidy designs that set an income cap and provide additional incentives to lower-income households could be more cost-effective in terms of boosting EV demand.