Office of Transportation and Air Quality

EPA-420-F-14-008

March 2014

EPA Sets Tier 3 Tailpipe and Evaporative 

Emission and Vehicle Fuel Standards

The U.S. Environmental Protection Agency (EPA) is finalizing an 

important rule designed to reduce air pollution from passenger 

cars and trucks. Starting in 2017, Tier 3 sets new vehicle emissions 

standards and lowers the sulfur content of gasoline, considering the 

vehicle and its fuel as an integrated system. The vehicle standards 

reduce both tailpipe and evaporative emissions from passenger cars, 

light-duty trucks, medium-duty passenger vehicles, and some heavyduty vehicles. The gasoline sulfur standard will make emission control 

systems more effective for both existing and new vehicles, and will 

enable more stringent vehicle emissions standards since removing 

sulfur allows the vehicle’s catalyst to work more efficiently. The Tier 

3 standards are closely coordinated with California’s LEV III standards as well as with EPA’s and California’s programs for greenhouse 

gas (GHG) emissions from light-duty vehicles. EPA is setting these 

Tier 3 standards to address public health issues that exist currently 

and are projected to continue in the future. EPA’s action was requested 

in a May 21, 2010 Presidential memorandum.

The Tier 3 program continues the successful transition that began with EPA’s Tier 2 

program, finalized in 2000, in which EPA treated vehicles and fuels as a system to 

reduce both gasoline sulfur and vehicle emissions. While there were claims at the 

time that the program would cause fuel prices to increase far in excess of EPA’s estimates and would result in closures and fuel supply shortages, the Tier 2 program was 

a success; it resulted in gasoline sulfur reductions of up to 90 percent and enabled the 

use of new emission control technologies in cars and trucks with no serious negative impacts on the refining industry. EPA’s Clean Diesel Program similarly utilized a 

systems approach to reducing sulfur emissions from diesel fuels and enabling cleaner 

diesel technologies with the Highway Diesel Rule (finalized in 2001) and the Nonroad Diesel Rule (finalized in 2004), again with no serious negative impacts. Now 

that the U.S. refining industry routinely produces lower sulfur fuel products, new 

market opportunities for international fuel exports have opened up. 

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EPA is finalizing the Tier 3 program largely as proposed. EPA received a large number and wide 

range of comments on the proposed rule, and the final Tier 3 program is based both on this 

extensive public input and updated analyses of the rule’s impacts. EPA sought comment on the 

level of the per-gallon sulfur cap (which applies in addition to the annual average), and has 

decided to maintain the per-gallon caps at existing levels. EPA is also finalizing an ethanol 

content of 10 percent (E10) for emissions test gasoline (as opposed to the proposed 15 percent 

ethanol (E15) test fuel). 

Tailpipe Emissions Standards 

EPA is setting new tailpipe standards for the sum of non-methane organic gases (NMOG) and 

nitrogen oxides (NOX), presented as NMOG+NOX, and for particular matter (PM) that apply 

to all light-duty vehicles and some heavy-duty vehicles. Compared to current standards, the 

NMOG and NOX tailpipe standards for light-duty vehicles represent approximately an 80% 

reduction from today’s fleet average and a 70% reduction in per-vehicle PM standards. Heavyduty tailpipe standards represent about a 60% reduction in both fleet average NMOG+NOX 

and per-vehicle PM standards. EPA is also extending the regulatory useful life period during 

which the standards apply from 120,000 miles to 150,000 miles. 

The tailpipe standards include different phase-in schedules that vary by vehicle class, but generally phase in between model years 2017 and 2025. In addition to the gradual phase-in schedules, 

several other provisions are designed to further ease manufacturers’ paths to compliance with 

the stringent new standards. Depending on the standards and the vehicle class, these flexibility 

provisions include credits for early compliance and the ability to offset some higher-emitting 

vehicles with extra-clean models. EPA is also finalizing more lead time for small businesses 

and small volume manufactures as well as a hardship provision that allows for additional time 

to comply if a manufacturer cannot meet requirements after a good faith effort and would face 

severe economic hardship without the additional lead time.

NMOG+NOX Standards: The standards for NMOG+NOX are fleet-average standards, meaning that a manufacturer calculates the weighted average emissions of the vehicles it produces in 

each model year and compares that average to the applicable standard for that model year. The 

standards differ by vehicle class and test cycle. Key elements include: 

 NMOG+NOX Standards for Light-Duty Vehicles and Light-Duty Trucks (vehicles 

 below 8,500 pounds (lbs) Gross Vehicle Weight Rating (GVWR)), and Medium-Duty 

 Passenger Vehicles (8,500 to 10,000 lbs GVWR): 

•	 As measured on the Federal Test Procedure (FTP), the standards decline from 

today’s fleet average of 160 milligrams per mile (mg/mi) to 30 mg/mi by 2025. 

•	 As measured on the Supplemental Federal Test Procedure (SFTP), the standards 

decline from today’s fleet average of about 200 mg/mi to 50 mg/mi by 2025. 

 NMOG+NOX Standards for Heavy-Duty Pick-ups and Vans; Class 2b (8,501-10,000 lbs 

 GVWR) and Class 3(10,001-14,000GVWR)): 
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•	 As measured on the FTP, the fleet average standards decline from today’s fleet 

average of 395 mg/mi to 178 mg/mi for Class 2b vehicles and 630 mg/mi to 

247 mg/mi for Class 3 vehicles by 2022.

•	 Additional standards for emissions measured over a heavy-duty SFTP are being 

set for the first time and vary by vehicle class and power-to-weight ratio. 

PM Standards: The PM standards are expressed on a per-vehicle basis, meaning the standards 

apply to each vehicle separately (i.e., not as a fleet average). EPA is setting PM standards that 

differ by vehicle class and test cycle. Key elements include: 

 PM Standards for Light-Duty Vehicles, Light-Duty Trucks, and Medium-Duty Passenger 

 Vehicles:

•	 As measured on the FTP, the per-vehicle standard is 3 mg/mi for all vehicles and 

for all model years, as compared to today’s standard of 10 mg/mi. 

•	 As measured on the US06, a high-speed, fast-acceleration component of the 

SFTP, the standard for all light-duty vehicles is 10 mg/mi through MY 2018 and 

6 mg/mi for 2019 and later model years. These standards are lower than what was 

proposed based on more recent data supporting a numerically lower US06 PM 

standard. 

 PM Standards for Heavy-Duty Pick-ups and Vans; Class 2b and 3: 

•	 As measured on the FTP, the per-vehicle PM standards are 8 mg/mi for Class 2b 

vehicles and 10 mg/mi for Class 3 vehicles. 

•	 EPA is also setting PM standards for emissions measured over the SFTP with 

standards levels and duty cycles varying by vehicle class and power-to-weight 

ratio. 

Evaporative Emission Standards 

EPA is setting more stringent standards designed to eliminate fuel vapor-related evaporative 

emissions and improve durability. The evaporative emissions program represents about a 50 percent reduction from current standards and applies to all light-duty and onroad gasoline-powered 

heavy-duty vehicles. As with the tailpipe standards, the evaporative emissions standards include 

phase-in flexibilities, credit and allowance programs, and more lead time and a hardship provision for small businesses and small volume manufacturers. EPA is also extending the regulatory 

useful life period during which the standards apply from 120,000 miles to 150,000 miles. Key 

elements of the program include:

 Evaporative Emissions Standards: The final standards over 2-day and 3-day evaporative 

 emission tests vary by vehicle categories and range from 0.300 g/test to 0.500 for light- 

 duty vehicles and medium duty passenger vehicles, with 0.600 g/test for onroad gasoline- 

 powered heavy-duty vehicles. 
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 Bleed Test Requirements: EPA is setting a new testing requirement referred to as the 

 bleed emission test. The bleed emissions test standard for light-duty and medium-duty 

 passenger vehicles is 0.020 g/test without averaging. The standard for onroad gasoline- 

 powered heavy-duty vehicles is 0.030 g/test without averaging. 

 Leak Test and Emission Standard: EPA is finalizing a new emission standard and test 

 procedure requiring that the cumulative equivalent diameter of any orifices or “leaks” 

 not exceed 0.02 inches anywhere in the fuel/evaporative system for light-duty vehicles, 

 medium-duty passenger vehicles, and some gasoline-powered heavy-duty vehicles. 

 Onboard Diagnostic System (OBD) Requirements: EPA is adopting and incorporating 

 by reference the California Air Resources Board’s (CARB) current OBD regulations, 

 effective for MY 2017, with only minor differences. These requirements cover all vehicles 

 except those in the heavier fraction of the heavy-duty vehicle class.

Fuel Standards

EPA is finalizing gasoline sulfur reductions that are critical to enabling manufacturers to comply 

across the fleet with the stringent vehicle standards. The gasoline sulfur standards will also 

achieve significant immediate benefits by reducing emissions from existing vehicles. Under the 

final Tier 3 program, federal gasoline will be required to meet an annual average standard of 10 

parts per million (ppm) of sulfur by January 1, 2017. EPA is also finalizing standards that maintain the current 80 ppm refinery gate and 95 ppm downstream cap. The Tier 3 gasoline sulfur 

standards are similar to levels already being achieved in California, Europe, Japan, South Korea, 

and several other countries.

For the gasoline sulfur standards, EPA is finalizing averaging, banking, and trading (ABT) program that allows refiners and importers to spread out their investments through an early credit 

program and rely on ongoing nationwide averaging to meet the 10 ppm sulfur standard. New 

to the final rule, EPA is including the ability to carry over credits from Tier 2 to Tier 3 in the 

ABT program. EPA is also finalizing a three-year delay for small refiners and small volume refineries processing 75,000 barrels of crude oil per day or less, as well as other flexibilities for refiners 

such as hardship provisions for extenuating circumstances. 

Emissions Test Fuel

EPA is updating the federal emissions test fuel to better match today’s in-use gasoline and also to 

be forward-looking with respect to future ethanol and sulfur content. The new test fuel specifications apply to new vehicle certification, assembly line, and in-use testing. EPA is transitioning 

to the new test fuel during the first few years that the Tier 3 tailpipe and evaporative standards 

are phasing in. Key changes include moving to a test fuel containing 10 percent ethanol by volume, lowering octane, and lowering the existing sulfur specification to be consistent with Tier 3 

requirements. EPA is also setting test fuel specifications for E85 for the first time.
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Public Participation

This final rule is based on extensive public input received in response to the Tier 3 proposal. 

EPA held two public hearings in Philadelphia and Chicago, and we received more than 200,000 

public comments. A broad range of stakeholders provided comments, including state and local 

governments, auto manufacturers, emissions control suppliers, refiners, fuel distributors and others 

in the petroleum industry, renewable fuels providers, environmental organizations, consumer 

groups, labor groups, private citizens, and others. EPA has also had extensive outreach with key 

stakeholders throughout the development of this rule.

For More Information

You can access the final rule and related documents on EPA’s Office of Transportation and Air 

Quality (OTAQ) Web site at: 

www.epa.gov/otaq/tier3.htm

For more information on this rule, please contact the U.S. Environmental Protection Agency, 

Office of Transportation and Air Quality at: 

E-mail: otaq@epa.gov