CO2 and Fuel Consumption Standards

Both EPA’s and NHTSA’s joint final standards for the three main heavy-duty regulatory categories are summarized below.

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) and 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. The agencies have adopted differentiated standards for nine subcategories of combination tractors based on three attributes: weight class, cab type and roof height. The standards will phase in to the 2017 levels shown in Table 1. These final standards will achieve from nine to 23 percent reduction in emissions and fuel consumption from affected tractors over the 2010 baselines.

  EPA Emission Standards (g CO₂/ton-mile) NHTSA Fuel Consumption Standards (gal/ 1,000 ton-mile)
    Low roof   Mid 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

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. This approach recognizes both the inherently higher GHG emissions and fuel consumption of higher-capacity vehicles, and the importance of payload and towing capacity to the owners of these work trucks and vans.

EPA has established standards for this segment in the form of a set of target standard curves, based on a “work factor” that combines a 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 of 17 percent for diesel vehicles and 12 percent for gasoline vehicles, compared to a common baseline.

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 of 15 percent for diesel vehicles and 10 percent for gasoline vehicles, compared to a common baseline.

To satisfy lead time requirements under EISA, NHTSA standards will be voluntary in 2014 and 2015. Both agencies are providing manufacturers with two alternative phase-in approaches that get equivalent overall reductions. One alternative phases the final standards in at 15-20-40-60-100 percent in model years 2014-2015-2016-2017-2018. The other phases the final standards in at 15-20-67-67-67-100 percent in model years 2014-2015-2016-2017-2018-2019.

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 – Light Heavy (Class 2b through 5), Medium Heavy (Class 6 and 7), and Heavy Heavy (Class 8), which is consistent with the engine classification.

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 Table 2 represent emission reductions from six to nine percent, from a 2010 baseline.

Vocational Vehicle Standards

  EPA Full Useful Life Emissions Standards( gCO₂/ton-mile) NHTSA Fuel Consumption Standards(gal/1,000 ton-mile)
Light Heavy Class 2b-5 373   36.7  
Medium Heavy Class 225 22.1
Heavy Heavy Class 8 222 21.8

EPA’s N2O, CH4 and Air Conditioning Leakage Standards

In addition to the CO2 standards described above, EPA has adopted standards for N2O and CH4 emissions. N2O and CH4 are important GHGs 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.

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, while the standard for smaller A/C systems (capacity of 733 grams or less) is measured in grams of refrigerant leakage per year.

Program Flexibilities

EPA’s and NHTSA’s final HD National Program provides flexibilities to manufacturers in terms of how they can comply with the new standards. These flexibilities are expected to provide sufficient lead time for manufacturers to make necessary technological improvements and reduce the overall cost of the program, without compromising overall environmental and fuel consumption objectives.

The primary flexibility provisions are an engine averaging, banking, and trading (ABT) program and a vehicle ABT program. These ABT programs will allow for emission and fuel consumption credits to be averaged, banked, or traded within each of the defined averaging sets. There are three weight-based averaging sets for two of the regulatory categories: combination tractors and vocational vehicles. The pickup trucks and vans are one fleetwide averaging set, and there are four averaging sets for engines.

In addition to the general ABT programs, EPA is providing engine manufacturers and heavy-duty pickup and van manufacturers the added option of using CO2 credits to offset CH4 or N2O emissions that exceed the applicable emission standards based on the relative global warming potentials of these emissions.

The structure of the ABT program for HD engines is based closely on earlier EPA ABT programs for HD engines; the program for pickup trucks and vans is built on the existing light-duty GHG and fuel economy credit carry-forward, carry-back, and trading provisions; and first-time ABT provisions are adopted for other HD vehicle manufacturer that are as consistent as possible with the provisions for other categories.

The agencies have adopted three additional optional credit opportunities. The first is an early credit option intended for manufacturers who demonstrate improvements in excess of the standards prior to the model year that they become effective. The second is a credit program intended to promote implementation of advanced technologies, such as hybrid powertrains, engines with Rankline cycle waste heat recovery systems, and electric or fuel cell vehicles. The last credit intended to apply to new and innovative technologies that reduce vehicle CO₂ emissions and fuel consumption, for which the benefits are not captured over the test procedure used to determine compliance with the standards (i.e. “off-cycle”).


In Europe, The Regulation (EU) 2019/1242 sets the CO₂ emission standards for heavy-duty vehicles. The Regulation entered into force on 14th August 2019. The regulation was implemented to achieve greenhouse gas emissions by 30% by 2030, to achieve the Paris Agreement objectives, to set out new performance requirements for heavy-duty vehicles by reducing the amount of CO₂ emissions. According to article 2, the regulation applies to N₂ and N₃ heavy-duty vehicles that have the following characteristics: tractors with an axle configuration of 6×2, rigid lorries with an axle configuration of 6×2, tractors with an axle configuration of 4×2, a technically permissible maximum laden mass exceeding 16 tonnes; and rigid lorries with an axle configuration of 4×2 and a technically permissible maximum laden mass exceeding 16 tonnes.

Article 4 of the Regulation(EU) states that starting from 1 July 2020, the commission shall determine the average specific emissions for manufacturers in g/tkm by taking into account the zero- and low-emission factor and the data reported pursuant to Regulation(EU) 2018/956 for the manufacturer’s new heavy-duty vehicles registered in the preceding reporting period, excluding vocational vehicles. Article 5 states that as from 1 July 2020, the Commission shall determine for each manufacturer the zero- and low-emission factor for the preceding reporting period. The zero- and low-emission factor shall take into account the number and the CO₂ emissions of zero- and low-emission heavy-duty vehicles in the manufacturer’s fleet in a reporting period, including zero-emission heavy-duty vehicles as well as zero- and low-emission vocational vehicles.

Article 6 states that as from July 1 2026 and in the subsequent reporting period, the commission shall determine for each manufacturer a specific CO₂ emissions target shall be the sum over all vehicle sub-groups, of the products of the following values: the reference CO₂ emissions; the manufacturer’s share of vehicles in each vehicle sub-group; the annual mileage and payload weighting factors applied to each vehicle sub-group.

Article 8 sets the emissions targets that are compliant with the specific CO₂ targets. Article 8(2) states the limits of CO₂ emissions:

  1. Where in any of the reporting periods of the years 2025 to 2028, the sum of the emission debts reduced by the sum of the emission credits exceeds the emission debt of 5%
  2. Where, in the reporting period of the year 2029, the sum of the emission debts reduced by the sum of the emission credits is positive
  3. Where, from the reporting period of the year 2030 onwards, the manufacturer’s average specific CO₂ emissions exceed its specific CO₂ emission target

Article 8(1) of the EU regulation sets the premiums that will be imposed should the CO₂ be in excess:

  1. From 2025 to 2029

(Excess CO₂ emissions premium) = (Excess CO₂ emissions x 4 250 EUR/gCO₂/tkm)

  1. From 2030 onwards

(Excess CO₂ emissions premium = (Excess CO₂ emissions x 6 800/EUR/gCO₂/ tkm).

In conclusion, the excess CO₂ emissions premiums shall be considered as revenue for the general budget of the European Union.


Asia has modelled its vehicle emission standards after the European Standard. Asia’s current nationwide emissions standard is the Euro IV (4). Asia intends to implement Asia 5 standard for LDVs in 2018 while the implementation of HDVs has yet to be determined. Asia is encouraging the purchase of hybrid and electric cars to reduce vehicle emissions. In Asia, fuel tax is an alternative policy i.e. the larger the engine and fuel requirement, the higher the amount of tax one is required to pay. This will help reduce fuel consumption hence reducing emission of gases into the environment (Owen and Tao 2015, 9).


Owen D. and Tao J. (2015), International Best Practices For Emissions and Fuel Standards: Implementation Possibilities for Asean, Energy Studies Institute, National University of Singapore, Volume 2, No. 1/2015

Regulatory Announcement 2012

The Regulation (EU) 2019/1242

United States Environmental Protection Agency 2012

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