EPA & NHTSA 2017–2025 GHG and Fuel Economy Rules


The EPA and the National Highway Traffic Safety Administration (NHTSA) have finalized new greenhouse gas (GHG) and fuel economy (FE) rules for model years 2017–2025 light-duty vehicles. The new GHG emission rules, when fully phased in, will require an average fuel economy of 54.5 miles per gallon (mpg) (fleet average of 163 grams/mile of CO2 equals 54.5 mpg). The rules, however, allow automakers to earn GHG and FE credits, in part by producing NGVs and other advanced technology vehicles, so actual fleet averages are expected to be less than 54.5 miles. NHTSA’s fuel economy regulations actually specify a fuel economy average of 49.6 mpg by 2025.

Additionally, the U.S. EPA and NHTSA finalized FE and GHG for medium and heavy-duty vehicles. The regulations start to take effect in 2014 and are fully phase-in by 2018. The fuel efficiency regulations actually lag the GHG rules by two years, not taking effect until 2016. Summarizing the rules is not easy because the rules are extensive and establish different requirements for different types of vehicles, segregating vehicles as follows: (1) combination tractors; (2) heavy-duty pickup trucks and vans; and (3) vocational vehicles. The phase-in periods and levels of stringency also vary depending on whether an engine is spark-ignited or compression ignited.

When implemented, the standards for combination tractors would achieve a 9 to 23 percent reduction in emissions and fuel consumption compared to 2010 baseline levels. For heavy-duty pickups and vans, the rules would require greenhouse gas emission reductions of 17 percent for diesel vehicles and 12 percent for gasoline vehicles. The fuel economy requirements for such vehicles would require a 15 percent improvement for diesel vehicles (10 percent for gasoline). The greenhouse gas rules regulate CO2 emissions by imposing an overall fleet-wide average, but impose a per vehicle/engine cap on methane and nitrous oxide emissions. Manufacturers that have trouble meeting the caps imposed on these other pollutants may use CO2 credits to offset them. The methane cap finalized for heavy duty engines is 0.10 grams per bhp-hr.

NGVAmerica submitted comments and recommendations to the agencies, and, while not all of them were accepted, several were. Under the new rules, manufacturers that produce dedicated and bi-fuel NGVs will receive temporary GHG emission credits for model years (MY) 2017–2021 in addition to the fuel economy incentives already in place. The credits will reward manufactures for producing NGVs. Each NGV sold counts as 1.6 NGVs in MY 2017–2019, 1.45 in MY 2020, and 1.3 in MY 2021. Since NGVs have lower GHG emissions than comparable gasoline vehicles, the sales multiplier helps to lower a manufacturer’s over all emissions average. Rules previously finalized by the agencies for MY 2012–2015 also provide enhanced GHG credits for NGVs.

The new rules also finalize changes to existing GHG regulations for 2012–2016 that will allow NGV bi-fuel manufacturers to make use of “utility factors.” The utility factors are based on the driving range of the NGV, and they enable manufacturers to substitute a much higher natural gas utilization rate for purposes of the greenhouse gas calculations. The current rules assume a default utilization rate of 50 percent natural gas and 50 percent gasoline for bi-fuel vehicles. Under the new rules, most bi-fuel vehicles will be credited with a much higher natural gas utilization rate, which will result in slightly improved greenhouse gas emussions credits for NGVs. The final rules, however, include two conditions not included in the proposed rules. To qualify for the utility factors, the bi-fuel NGV (1) must operate on natural gas until it runs out of natural gas, and (2) the vehicle must have a 2:1 driving range on natural gas (go twice as far on natural gas). Another major benefit of the utility factors is that they will be used to measure fuel economy for bi-fuel NGVs beginning with model year 2020. NGVAmerica had requested that the utility factors be used for fuel economy as early as 2012 but the agencies objected, arguing their statutory authority would not permit it.

For more information, follow these links:
EPA final rule and supporting documents
VNG.CO Summary and Analysis