关键词：大气；空气污染；空气健康
摘 要：In August 2012, the U.S. Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) announced the final standard governing new-vehicle fuel economy for model years 2017 through 2025. The new standard maintains the current system of incremental increases in Corporate Average Fuel Economy (CAFE) requirements for new light-duty vehicles each model year, based on targeted decreases averaging approximately 5% per year in CO2 output per mile. This report compares the recent improvements in fuel economy with the projected CAFE performance levels anticipated by NHTSA. Recent trends in CAFE performance, when compared with the performance levels projected to be achieved by NHTSA, indicate that achieved CAFE performance has exceeded these anticipated levels for 2012 and 2013 model years--the two years that the current standard has been in effect. Additionally, achieved CAFE performance has consistently increased annually from model year 2008 through model year 2013. If the current trends in annual improvements continue, future CAFE performance is expected to continue meeting or exceeding the projected performance levels (and desired greenhouse gas reductions) contained in the latest CAFE standards.