US Government Announces Fuel Efficiency Program for Heavy Duty Trucks and Buses

  • By: Staff Editor
  • Date: August 19, 2011
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The US’ need to reduce oil consumption and global climate change led the NHTSA and EPA to adopt the Heavy Duty (HD) National Program. The program aims at reducing fuel use and GHG emissions from on-highway transportation sources. The agencies state that these actions will lead to:

  • Improved energy security,
  • Increased fuel savings,
  • Reduced GHG emissions,
  • Regulatory certainty for manufacturers.

Transportation accounts for about 77 percent of the US’ domestic oil use with heavy-duty vehicles account for about 17 percent of transportation oil use. Transportation sources emitted 29 percent of all U.S. GHG emissions in 2007 and have been the fastest-growing source of U.S. GHG emissions since 1990.

The new fuel efficiency standards take effect with the 2014 model year. The program includes standards for:

  • Combination tractors
  • Heavy-duty pick up trucks and vans
  • Vocational vehicles

The EPA’s N2O, CH4 and Air Conditioning Leakage Standards are also included in the program.

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Expected savings and costs

Agencies estimate that the combined standards will:

  • Reduce CO2 emissions by about 270 million metric tons
  • Save about 530 million barrels of oil over the life of model year 2014 to 2018 vehicles.
  • Yield an estimated $50 billion in net benefits over the life of model year 2014 to 2018 vehicles, resulting in significant long-terms savings for vehicle owners and operators.

A semi-truck operator could pay for the technology upgrades in under a year and realize net savings of $73,000 through reduced fuel costs over the truck’s useful life.  These cost saving standards will also reduce emissions of harmful air pollutants like particulate matter, which can lead to asthma, heart attacks and premature death.

Applicability across vehicle categories

By the 2018 model year, the program is expected to achieve significant savings relative to current levels, across vehicle categories. 

Combination tractors

Heavy-duty combination tractors – the semi trucks that typically pull trailers - are built to move freight. Freight transportation customers choose tractors primarily based on two major characteristics:

  • The gross vehicle weight rating (GVWR, which establishes the maximum carrying capacity of the tractor and trailer)
  • Cab type (sleeper cabs provide overnight accommodations for drivers).

Operators also consider the tractor roof height when mating with trailers for the most efficient configuration. Therefore, the agencies have adopted differentiated standards for nine sub-categories of combination tractors based on three attributes:

  • Weight class
  • Cab type and
  • Roof height

The standards will phase in to the 2017 levels as shown in the table below:


EPA Emission Standards (g CO2/ton-mile)
NHTSA Fuel Consumption Standards (gal/1000 ton-mile)
  Low Roof Low Roof High Roof Low Roof Mid Roof High Roof
Day Cab Class 7 104 115 120 10.2 11.3 11.8
Day Cab Class 8 80 86 89 7.8 8.4 8.7
Sleeper Cab Class 8 66 73 72 6.5 7.2 7.1


These final standards are expected to achieve from nine to 23 percent reduction in emissions and fuel consumption from affected tractors over the 2010 baselines.

Heavy-duty pickup trucks and vans

The agencies are setting corporate average standards for heavy-duty pickup trucks and vans, similar to the approach taken for light-duty vehicles. Each manufacturer’s standard for a model year depends on its sales mix, with higher capacity vehicles (payload and towing) having numerically less stringent target levels, and with an added adjustment for 4-wheel drive vehicles.

The EPA has established standards for this segment in the form of a set of target standard curves, based on a “work factor” that combines:

  • The vehicle’s payload,
  • Towing capabilities, and
  • Whether or not it has 4-wheel drive.

The standards will phase in with increasing stringency in each model year from 2014 to 2018. The EPA standards adopted for 2018 (including a separate standard to control air conditioning system leakage) represent an average per-vehicle reduction in GHG emissions, compared to a common baseline, of:

  • 17 percent for diesel vehicles
  • 12 percent for gasoline vehicles

The NHTSA is setting corporate average standards for fuel consumption that are equivalent to EPA‘s standards (though not including EPA’s final air conditioning leakage standard). The final NHTSA standards represent an average per-vehicle improvement in fuel consumption, compared to a common baseline, of:

  • 15 percent for diesel vehicles
  • 10 percent for gasoline vehicles

Vocational vehicles

Vocational vehicles consist of a very wide variety of truck and bus types including delivery, refuse, utility, dump, cement, transit bus, shuttle bus, school bus, emergency vehicles, motor homes, tow trucks, and many more.

Vocational vehicles undergo a complex build process, with an incomplete chassis often built with an engine and transmission purchased from different manufacturers, which is then sold to a body manufacturer.

In these rules, the agencies are regulating chassis manufacturers for this segment. The agencies have divided this segment into three regulatory subcategories, consistent with engine classification:

  • Light Heavy (Class 2b through 5)
  • Medium Heavy (Class 6 and 7)
  • Heavy Heavy (Class 8)

After engines, tires are the second largest contributor to energy losses of vocational vehicles. The final program for vocational vehicles for this phase of regulatory standards is limited to tire technologies (along with the separate engine standards). The standards depicted in the table below represent emission reductions from six to nine percent, from a 2010 baseline for the MY 2017.


  EPA Full Useful Life Emissions Standards (g CO2/ton-mile) NHTSA Fuel Consumption Standards (gal/1,000 ton-mile)
Light Heavy Class 2b-5 373 36.7
Medium Heavy Class 6-7 225 22.1
Heavy Heavy Class 8 222 21.8


EPA’s N2O, CH4 Leakage Standards

In addition to the CO2 standards, the EPA has adopted standards for N2O and CH4 emissions. N2O and CH4 are important greenhouse gases that contribute to global warming, more so than CO2 for the same amount of emissions. While today’s gasoline and diesel engines emit relatively low levels of N2O and CH4 emissions, EPA’s standards will act to cap emissions to ensure that manufacturers do not allow the N2O and CH4 emissions of their future engines to increase significantly above the currently controlled low levels.

EPA’s Air Conditioning Standards

Air conditioning (A/C) systems contribute directly to GHG emissions through leakage of HFC refrigerants, which are powerful GHG pollutants. EPA has adopted standards to assure that high-quality, low-leakage components are used in each air conditioning system designed for heavy-duty pickup trucks and vans, and semi trucks.

  • The standard for larger A/C systems (capacity above 733 grams) is measured in percent total refrigerant leakage per year
  • The standard for smaller A/C systems (capacity of 733 grams or less) is measured in grams of refrigerant leakage per year

Additional Standards

-    Read the new heavy duty vehicle fuel efficiency regulations in full

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