California Air Resources Board

Since 1990, CARB’s Low-Emission Vehicle (LEV) regulations have set increasingly stringent standards to reduce smog-forming pollutants, toxic air contaminants, and greenhouse gases from light-duty cars and trucks. These requirements have driven the development of cleaner technologies, improved air quality, and delivered significant public health benefits across California. Most recently, the LEV regulation was included in the Advanced Clean Cars Program, which combined multiple vehicle standards into a coordinated approach to reducing emissions.

A New Phase of Vehicle Standards

In response to illegal federal actions purporting to revoke California’s Clean Air Act waiver for the enforcement of the Advanced Clean Cars II regulations, Governor Gavin Newsom signed Executive Order N-27-25 on June 12, 2025. This order reaffirms the state’s commitment to cut harmful air pollution from transportation and protect public health.

CARB staff has begun a new phase of work that includes light-duty vehicle emissions standards to reduce criteria air pollutant, greenhouse gas, and toxic emissions consistent with State and federal law. To learn about CARB’s new phase of vehicle standards, visit the Drive Forward Vehicle Standards page.

History of LEV Regulations

LEV I (1990–2003 model years)
CARB adopted the first LEV regulations in 1990, requiring automakers to produce progressively cleaner light- and medium-duty vehicles with more durable emission controls. Key elements included:

• The most stringent exhaust standards ever adopted for these vehicle classes.
• A phase-in mechanism requiring cleaner vehicles each year, with credit banking and trading options.
• A requirement that a portion of sales be zero-emission vehicles (ZEVs) with no exhaust or evaporative emissions.

LEV II (2004–2010 model years)
Building on LEV I, the LEV II regulations required further reductions in criteria pollutant emissions from light- and medium-duty vehicles, beginning with the 2004 model year.

LEV Greenhouse Gas Standards (2009–2016 model years)
In 2004, CARB approved the landmark Pavley regulations, the nation’s first standards to reduce greenhouse gas emissions from passenger vehicles. After U.S. EPA adopted federal greenhouse gas standards essentially equivalent to CARB’s[DW1] , California allowed automakers to comply with its standards by demonstrating compliance with the federal standards through a “deemed to comply” option for the 2012–2016 model years.

LEV III (2015–2025 model years)
In 2012, CARB adopted the LEV III regulations as part of the first Advanced Clean Cars package, alongside the ZEV program. LEV III included increasingly stringent limits on criteria pollutants and greenhouse gases through the 2025 model year.

LEV IV (2026–2035 model years) - what do we say here and where do we link?
In 2022, CARB adopted LEV IV regulations as part of the Advanced Clean Cars II rulemaking, establishing the next generation of low- and zero-emission vehicle standards. LEV IV supports California’s efforts to meet federal ozone standards and achieve carbon neutrality by 2045. [Formal regulatory documents can be found here.]

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