Proposed Standards

It is important to note that the joint proposed standards cover not only engines but also the complete vehicle, allowing the agencies to achieve the greatest possible reductions in fuel consumption and GHG emissions, while avoiding unintended consequences. The majority of these vehicles carry payloads of goods or equipment, in addition to passengers. To account for this in the regulatory program, two types of standard metrics are proposed: payload-dependent gram per mile (and gallon per 100-mile) standards for pickups and vans; and gram per ton-mile (and gallon per 1,000 ton-mile) standards proposed for vocational vehicles and combination tractors. These proposed metrics account for the fact that the work to move heavier loads burns more fuel, and emits more CO2 than in moving lighter loads.

The joint proposed standards are rooted in regulatory history, EPA’s SmartWay Transport Partnership program, and extensive technical and engineering analyses. In developing this HD National Program, the agencies have drawn from the SmartWay Transport Partnership Program experience to identify technologies as well as operational approaches that fleet owners, drivers, and freight customers can incorporate. NHTSA and EPA believe that operational measures promoted by SmartWay can complement the proposed standards and provide benefits for the existing heavy-duty fleet.

The joint proposed standards are also heavily influenced by a study mandated by Congress in EISA and conducted for NHTSA by the National Research Council7 (footnotes). This study examined many aspects of heavy-duty vehicle fuel consumption as well as considerations for establishing fuel consumption standards.

CO2 and Fuel Consumption Standards

Both EPA’s and NHTSA’s joint proposed 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 are proposing differentiated standards for nine subcategories of combination tractors based on three attributes: weight class, cab type and roof height. The standards would phase in to the 2017 levels shown in Table 1. These proposed standards would achieve from seven to 20 percent reduction in emissions and fuel consumption from affected tractors over the 2010 baselines.
Table 1: Proposed MY 2017 Combination Tractor Standards EPA Emissions 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 7 103 103 116 10.1 10.1 11.4
Day Cab Class 8 78 78 86 7.7 7.7 8.5
Sleeper Cab Class 8 64 69 71 6.3 6.8 7.0

Heavy-Duty Pickup Trucks and Vans

The agencies are proposing to set 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 would depend 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 is proposing to establish 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 would phase in with increasing stringency in each model year from 2014 to 2018. The EPA standards proposed 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 proposing to set corporate average standards for fuel consumption that are equivalent to EPA‘s proposal (though not including EPA’s proposed air conditioning leakage standard). The proposed 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 would be voluntary in 2014 and 2015. Both agencies are proposing to provide 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 Trucks

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 other manufacturers, then sold to a body manufacturer. In these rules, the agencies are proposing to regulate chassis manufacturers for this segment. The agencies are proposing to divide 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 proposed program for vocational vehicles for this phase of regulatory standards is limited to tire technologies and hybrid powertrains (along with the separate engine standards). The proposed standards depicted in Table 2 represent emission reductions from seven to 10 percent, from a 2010 baseline.
Table 2: Proposed MY 2017 Vocational Vehicle Standards EPA Full Useful Life Emissions Standards (g CO2/ton-mile) NHTSA Fuel Consumption Standards (gal/1,000 ton-mile)
Light Heavy Class 3-5 344 33.8
Medium Heavy Class 6-7 204 20
Heavy Heavy Class 8 107 10.5

EPA’s Proposed N2O, CH4 and HFC Standards

In addition to the CO2 standards described above, EPA is proposing 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 proposed standards would 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 to GHG emissions in two ways – direct emissions through refrigerant leakage and indirect emissions due to the extra load on the vehicle’s engine to provide power to the air conditioning system. HFC refrigerants, which are powerful GHG pollutants, can leak from the A/C system. EPA is proposing a standard of 1.5 percent refrigerant leakage per year, to assure that high-quality, low-leakage components are used in each air conditioning system design for pickup trucks, vans, and tractors.

The proposed 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 would be voluntary in 2014 and 2015.