Vehicle Greenhouse Gas Emissions Standards
In 2002, California enacted AB 1493 (“Pavley Global Warming Bill”), a law that requires reductions in greenhouse gas emissions from light-duty vehicles. The California Air Resources Board (CARB) is responsible for setting the standards, which would apply to new vehicles starting in the 2009 model year, if CARB receives a waiver from the U.S. Environmental Protection Agency (EPA). The standard requires that new vehicles, on average, achieve an emissions reduction of 30 percent by 2016 and covers carbon dioxide, methane, nitrous oxide, and hydrofluorocarbon emissions.
Under the Federal Clean Air Act, California is the only state with the ability to set standards for motor vehicles, as long as these standards are as stringent as the federal standards and the state receives a waiver from the EPA. Once California receives a waiver from the federal government, other states can adopt California’s standards. More than fifteen states have adopted or have announced their intention to adopt the California standards.
September 2009: EPA and DOT’s National Highway Traffc Safety Administration (NHTSA) issued a joint proposal to establish a national vehicle standards program for light-duty vehicles. The EPA has proposed the frst-ever national greenhouse gas (GHG) emissions standards under the Clean Air Act, and NHTSA is proposing Corporate Average Fuel Economy (CAFE) standards under the Energy Policy and Conservation Act. The standards follow the targets stated by President Obama in May 2009. Under a previous agreement, California and those states that have adopted the California regulation have agreed to conform to the federal standard from 2012 to 2016. Read the "Proposed Rulemaking to Establish Light-Duty Vehicle Greenhouse Gas Emission Standards and Corporate Average Fuel Economy Standards" here . For more information about the standards, see here .
June 2009: EPA grants a waiver allowing California to regulate greenhouse gas (GHG) emissions from motor vehicles within the state, beginning with the 2009 model year. Although this waiver decision allows California to set its own standards for motor vehicles, and for other states to follow the California standard, California and the other states have agreed to conform to the federal standards announced by President Obama in May 2009 . Read the "Notice of Decision Granting a Waiverof Clean Air Act Preemption for California’s 2009 and Subsequent Model Year Greenhouse Gas Emission Standards for New Motor Vehicles" here .
May 2009: President Obama announces a national standard for passenger vehicles that will be set through a joint rulemaking process between the U.S. Environmental Protection Agency (EPA) and the U.S. Department of Transportation (DOT). By 2016, the federal standard will achieve the same fuel economy improvement as the California standard would have – 35.5mpg – and will also include a greenhouse gas emission limit per vehicle. Although the announcement does not specifically grant the California waiver, California has agreed to amend AB 1493 to conform to the federal standard from 2012 to 2016, if it receives a waiver to set its own vehicle standards after 2016 and enforce its own standards for model years 2009 to 2011. Under this agreement, automakers have also agreed to drop lawsuits against California’s proposed vehicle standard. Read more about the President’s announcement here  and California’s statement here . Read the Notice of Upcoming Joint Rulemaking between EPA and DOT here .
January 2009: President Obama directs the EPA to reconsider California’s waiver request. Read more here .
March 2008: EPA publishes “Notice of Decision Denying a Waiver of Clean Air Act Preemption for California's 2009 and Subsequent Model Year Greenhouse Gas Emission Standards for New Motor Vehicles.” View the notice here .
December 2007: In a letter to California Governor Arnold Schwarzenegger, EPA Administrator Stephen Johnson notifies the Governor that he will be denying California’s request for a waiver, stating that the request does not satisfy the requirements for a waiver under the Clean Air Act. Read the letter here .
December 2007: The Energy Independence and Security Act of 2007 is signed into law by President Bush. Among several climate-related provisions, the Act increases the federal Corporate Average Fuel Economy (CAFE) standards. The new standards require new passenger vehicles to achieve, on average, a fuel economy of 35 miles per gallon by 2020; National Highway and Traffic Safety Administration (NHTSA), under the U.S. DOT, is responsible for undertaking a rule-making process to set the standards. For more information about the Act, read more of Clean Air Act Preemption for California’s 2009 and Subsequent Model Year Greenhouse Gas Emission Standards for New Motor Vehicles" here .
September 2007: A Vermont judge rules that vehicle manufacturers can meet the new car standards as set by California without compromising vehicle safety. Read more .
April 2007: U.S. Supreme Court rules against vehicle manufacturers in Massachusetts v. EPA, finding that GHGs are a pollutant, that the EPA has the authority to regulate them under the Federal Clean Air Act, and that GHG emission standards under the Clean Air Act are not preempted by the federal fuel economy law. Read more .
February 2007: In a letter to CARB, EPA Acting Assistant Administrator William Wehrum explains that the Supreme Court decision in Massachusetts v. EPA is relevant to the waiver and that EPA intends to examine the waiver request after the Supreme Court issues its decision. Read the letter here .
December 2005: CARB submits waiver request to the U.S. EPA. Read more about the request here .
September 2004: CARB finalizes regulations to reduce greenhouse gas emissions from new motor vehicles, based on AB 1493. View the press release here .
July 2002: California Governor Gray Davis signs AB 1493, which directs CARB to adopt regulations that would achieve the “maximum feasible and cost-effective reduction of greenhouse gas emissions from motor vehicles.”
For More Information
• States Adopting Vehicle Greenhouse Gas Emissions Standards 
• Federal Vehicle Standards 
• EPA, California Greenhouse-Gas Waiver Request 
• California Air Resources Board, Climate Change for Mobile Sources 
• Assembly Bill 1493