The U.S. passenger car fleet consists of more than 200 million cars and light-duty trucks (referred to collectively as light-duty vehicles). When the Clean Air Act was enacted in 1970, almost all personal vehicles were cars. Today, at least half of all vehicle sales for personal use are sport utility vehicles (SUVs), vans and pickup trucks. Title II of the Clean Air Act required EPA to promulgate a series of rules to reduce passenger car tailpipe emissions, as well as emissions from refueling and the evaporation of gasoline in the tank. The regulation of vehicle tailpipe emissions is a statutory authority reserved for the federal government (the U.S. Environmental Protection Agency) with only one exception: The state of California may adopt and enforce its own vehicle tailpipe standards provided they are at last as stringent as the federal standards. Other states may opt into California’s vehicle standards, but may not adopt any vehicle standards that differ from the federal standards or California’s.
Today, new passenger cars, SUVs, cars and pickup trucks are over 90 percent cleaner than the cars of 1970 due to a rule adopted by EPA in 2000 – the “Tier 2” vehicle and gasoline sulfur rule – requiring all new passenger vehicles to meet tighter tailpipe emission standards beginning in 2004 and substantially cutting sulfur in gasoline to an average of 30 parts per million (ppm); lowering sulfur in gasoline not only results in direct emissions reduction benefits but also enables the use of advanced vehicle emission control technologies. And beginning in 2017, passenger cars and the gasoline they run on will become even cleaner under EPA’s “Tier 3” rule – adopted March 3, 2014 – which establishes even more rigorous vehicle tailpipe standards for new light-duty vehicles and further reduces sulfur in gasoline to an average of 10 ppm. The Tier 3 program will reduce emissions of pollutants that contribute to smog, particle pollution and haze, as well as emissions of toxic air pollutants, such as benzene, and result in a host of health benefits including, among others, the avoidance in 2030 of up to 2,400 premature deaths. The costs of this program are modest at less than a penny a gallon for the 10-ppm gasoline and $130 per vehicle.
In 2010, EPA and the U.S. Department of Transportation (DOT) jointly issued a final rule setting federal greenhouse gas emission standards and Corporate Average Fuel Economy (CAFE) standards for model year (MY) 2012 through 2016 passenger vehicles. This program was a step toward responding to President Obama’s call for a strong and coordinated federal greenhouse gas and fuel economy program. In 2012, EPA and DOT issued a second joint rule to extend the national program envisioned by the President to MYs 2017 through 2025 passenger vehicles.