The State of California is the largest purchaser of vehicles in the United States, and most of California’s greenhouse gas (GHG) emissions are the result of vehicle emissions. What would happen if the United States Environmental Protection Agency (USEPA) were to roll back emission standards on vehicles sold in California?

Brief History of Fuel Economy Standards

The Corporate Average Fuel Economy (CAFE) standards were implemented in the US in 1975 with the goal of improving the average fuel economy of cars and light trucks produced for sale in the US. California AB 1493 (Pavley Regulations and Fuel Efficiency Standards), enacted on July 22, 2002, took the US CAFE standards a step further by requiring the California Air Resources Board to develop and adopt regulations that reduce GHG emissions emitted by passenger vehicles and light duty trucks. Implementation of the regulation was delayed by lawsuits filed by automakers and by the USEPA’s denial of an implementation waiver. The USEPA subsequently granted the requested waiver in 2009, which was upheld by the US District Court for the District of Columbia in 2011. The standards were phased in during the 2009 through 2016 model years. When fully phased in, the near-term (2009–2012) standards were estimated to result in an approximately 22 percent reduction in GHG emissions compared with the 2002 fleet, and the mid-term (2013–2016) standards were estimated to result in about a 30 percent reduction.

The second phase of implementation for California AB 1493 was incorporated into Amendments to the Low-Emission Vehicle (LEV) Program, referred to as LEV III or the Advanced Clean Cars program. The Advanced Clean Car program combines the control of smog-causing pollutants and GHG emissions into a single coordinated package of requirements for model years 2017 through 2025, aiming to reduce GHG emissions from new cars by 34 percent from 2016 levels by 2025. The new rules will reduce pollutants from gasoline- and diesel-powered cars, and deliver increasing numbers of zero-emission technologies, such as full battery electric cars, newly emerging plug-in hybrid electric vehicles, and hydrogen fuel cell cars. The regulations will also ensure adequate fueling infrastructure is available for the increasing numbers of hydrogen fuel cell vehicles planned for deployment in California.

Effects of Fuel Economy Standards

The direct effect of vehicle fuel economy standards is that these standards require the auto industry to manufacture new vehicles with lower gas consumption than they would otherwise produce. California is the largest purchaser of vehicles in the US, and the precedent the State has been setting since 2002 has influenced the overall US auto manufacturing industry to produce more fuel-efficient vehicles nationwide.

Stricter vehicle fuel economy standards result in reduced transportation-related GHG emissions, which in turn results in reduced contribution to global warming and associated climate change effects. Climate change has a wide variety of harmful effects on communities in the US and across the world. Increased global temperatures have led to droughts, with the 2017 and 2018 wildfire seasons in California breaking size and damage records. Rising ocean temperatures have led to an increase in the frequency and intensity of major storms, including those that make landfall in the eastern United States. Other effects of climate change include air quality concerns, a higher frequency of droughts, an increase in storms and flooding, sea level rise, changes to the vectors of insects and thus infectious diseases, a decrease in water quality and supply from snowpack, and a decline in the health and productivity of forests.

The Future of Fuel Economy Standards

The USEPA is now considering whether or not it should deny California’s implementation waiver, which would allow the State to enforce greater GHG emissions reductions for passenger vehicles and light duty trucks. Given the influence of California’s policies, this could lead to a nationwide rollback in vehicle fuel economy standards—a major backwards step in US transportation-related GHG emissions reduction efforts. The denial of the waiver could contribute to an increase in the climate change effects that are already posing serious threats to US communities.

California’s fuel economy standards make a visible difference that goes beyond State lines. Overturning the implementation waiver for the next wave of GHG emissions regulations in the State would result in negative environmental, health, and financial impacts both within the State and nationwide.


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