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Key Issues, Websites and Programs related to Transportation, Air Pollution, and Climate Change

Overview: Pollutants and Programs

Vehicles and Engines

  • Automotive Trends Report: This report provides information about new light-duty vehicle greenhouse gas (GHG) emissions, fuel economy, technology data, and auto manufacturers' performance in meeting the agency’s GHG emissions standards.
  • Certification and Compliance for Vehicles and Engines: provides compliance information to the vehicle and engine industry about certifying vehicles and engines through EPA, including paying fees and reporting to ensure compliance.
  • Compliance and Fuel Economy Data: provides information about test data regarding vehicles emissions and fuel economy and how those certified emission levels and fuel economy label estimates are determined.
  • Emission Standards Reference Guide: contains federal emission standards for onroad and nonroad vehicles and engines, and related fuel sulfur standards.
  • Fuel Economyprovides information about fuel economy, the fuel economy label and fuel economy trends.
  • Green Vehicle Guide: helps consumers find information on vehicles that are more efficient and less polluting. The site also addresses transportation’s role in climate change.
  • Importing: outlines EPA’s requirements for importing a motor vehicle or engine into the United States.
  • Regulations for Emissions: provides information about emission standards and regulations for on-road and nonroad vehicles, engines and equipment.
  • State and Local Transportation: has information on ties between land use, transportation planning, and air quality. Find information on transportation conformity, policy and guidance and laws and regulations. 
  • Violations and Recalls:​ provides information about voided certificates, recalls and fuel economy estimates.
    • FCA (Fiat Chrysler Automobiles): provides information on alleged violations of the Clean Air Act including installing defeat devices in diesel Ram 1500s and Jeep Grand Cherokees sold in the United States.

    • VW (Volkswagen): provides information on EPA’s issued notice of violation (NOV) of the Clean Air Act (CAA) to Volkswagen. The NOV alleges software that circumvents EPA emissions standards for certain air pollutants.

Fuels and Fuel Additives

  • Diesel: provides information about diesel fuel programs including regulations that significantly reduce the sulfur content of diesel fuel.
  • Fuel Registration, Reporting and Compliance Help: provides information about the requirements for registration and health effects testing of new fuels or fuel additives and mandatory registration for fuels reporting and about mandatory reporting forms for parties regulated under EPA fuel programs.
  • Fuels Regulatory Streamlining: provides information about EPA’s work to streamline its gasoline and diesel fuel regulations.
  • Gasoline: provides information about EPA’s gasoline regulations, including the Tier 3 Gasoline Sulfur program, the Mobile Source Air Toxics rule, Reformulated Gasoline (RFG) regulations, and volatility requirements.
  • Renewable Fuels: provides information about regulations, developed by EPA, in collaboration with refiners, renewable fuel producers, and many other stakeholders, that ensure that transportation fuel sold in the United States contains a minimum volume of renewable fuel.


  • Clean Diesel and DERA: offers DERA funding in the form of grants and rebates as well as other support for projects that protect human health and improve air quality by reducing harmful emissions from diesel engines.
  • Ports Initiative: assists EPA and other participants to formulate strategies for moving forward on actions addressing the transportation, air quality and climate issues raised in the national conversations.
  • SmartWay: helps the freight transportation sector improve supply chain efficiency. SmartWay reduces transportation-related emissions, environmental risks for companies and increases global energy security.
  • Verified Technologies for SmartWay and Clean Diesel: provides information on evaluations and verifications of the emission reduction capabilities and durability of emission reduction technologies. 

Modeling, Testing and Research