ACEEE report makes recommendations for next phase of heavy-duty vehicle fuel economy and greenhouse gas regulations; evaluate the full vehicle, not components
The US Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) finalized the first fuel efficiency and greenhouse gas standards for heavy-duty vehicles—the new National HD Program— in August. (Earlier post.) The standards cover vehicles and engines of model years 2014 through 2019 and require fuel consumption reductions ranging from 5–24% for later years, depending on vehicle or engine class.
ACEEE, the American Council for an Energy Efficient Economy, notes that the current program will promote the adoption of certain efficiency technologies but not others, in part due to the structure of the program, which focuses on the efficiency of components rather than the vehicle as a whole. ACEEE has now released a new report—Heavy-Duty Vehicle Fuel Efficiency and Greenhouse Gas Emissions: The 2014–2019 Standards and a Pathway to the Next Phase—offering recommendations for the anticipated next phase of HD regulations in a dozen key areas.
Perhaps the most important aspect of the program to revisit in order to maximize the economic and environmental benefits of the program in the future is the treatment of tractor-trailers and vocational vehicles as collections of components, rather than as integrated systems. In the next phase, the performance of full vehicles, as sold, should be the basis for certification. This is a complex undertaking, however, and extensive data collection and model development will be required to take this step.—Khan and Langer
The authors offered the following recommendations to policymakers and the relevant agencies for the immediate future:
Trailer standards: Adopt trailer standards at the earliest possible date to increase fuel savings and allow integration of tractor and trailer improvements.
Data collection, analysis, and dissemination: Resume and expand the Vehicle Inventory and Use Survey or otherwise establish a federal data collection program for heavy-duty vehicles, including sales, configurations, fuel consumption, and driving patterns. Ensure data is publicly available. Collect in-use testing data through manufacturers, fleets, and federal agencies. Prepare annual reports on i) the state of the heavy-duty market and ii) fuel consumption and GHG emissions of new vehicles by vehicle type.
Vehicle simulation model: Develop and maintain a vehicle simulation tool that i) can accurately reflect all vehicle and drive cycle specifications relevant to fuel consumption and ii) is available for general use.
For the longer term, they recommend:
Full vehicle standards: Apply standards to the full vehicle as sold. Evaluate performance of tractor trucks with an appropriate, efficient trailer.
Vocational vehicle segmentation: Further segment vocational vehicles to reflect fundamental differences in duty cycles.
Vehicle test cycles and test weights: Reevaluate the ability of existing test cycles to capture current driving patterns for all vehicle classes, including road grade and driver behavior. Establish appropriate test weights based on vocation and weight class.
Test protocol: Require physical testing (road, track, or chassis dynamometer) for a basic set of well-defined vehicle configurations. Allow variations on these configurations to be tested using a simulation model.
Engine standard: For at least the next round of rulemaking, consider maintaining engine standards along with full-vehicle standards. Develop new test cycles for heavy-duty engines, reflecting real-world driving characteristics.
Heavy-duty pickups and vans: Bring heavy-duty pickups and vans to efficiencies consistent with those of their light-duty counterparts. Consider integrating the standards for heavy-duty pickup trucks and vans with the light-duty program while continuing to recognize the functional requirements of these vehicles.
Stringency: In determining the stringency of standards, consider technologies that deliver large lifetime savings, even if they do not pay back in the ownership period of the initial purchaser.
Buyer information: Put in place a permanent, buyer-oriented label for all covered vehicles, showing both certification values and separate fuel efficiencies for at least two relevant driving modes (e.g., urban and highway). Provide an online simulation tool to allow buyers to compare vehicle performance over drive cycles specified by the user.
Standards harmonization: Seek to achieve consistency with other regions regulating heavy- duty vehicle fuel efficiency or greenhouse gas emissions on program elements such as test cycles, measurement protocols, vehicle segmentation, and standard stringency, and thereby expand the market for efficiency technologies while streamlining manufacturer compliance.
A. Siddiq Khan and Therese Langer (2011) Heavy-Duty Vehicle Fuel Efficiency and Greenhouse Gas Emissions: The 2014–2019 Standards and a Pathway to the Next Phase (ACEEE Report Number T113)