National Research Council Report Explores Improving Fuel Economy of Medium- and Heavy-Duty Vehicles; Recommends Immediately Beginning Developing a Regulatory Approach

. For other vehicle classes, the financial investments in making improvements would be cost-effective at higher prices of fuel.

Among the major findings from the study are:

• While it may seem expedient to initially focus on those classes of vehicles with the largest fuel consumption (i.e., Class 8, Class 6, and Class 2b, which together account for approximately 90 percent of fuel consumption of MHDVs),
  selectively regulating only certain vehicle classes would lead to very serious unintended consequences and would compromise the intent of the regulation. Within vehicle classes, there may be certain subclasses of vehicles (e.g., fire trucks) that could be exempt from the regulation without creating market distortions.

• Large OEMs, with significant engineering capability, design and manufacture almost all Class 2b, 3, and 8b vehicles. Small companies with limited engineering resources make a significant percentage of vehicles in Classes 4
  through 8a, although in many cases they buy the complete chassis from larger
  OEMs. Regulators will need to take the limitations of these smaller companies into account.

• Commercial trailers are produced by a separate group of manufacturers that are not associated with truck manufacturers. Trailers, an important opportunity for fuel consumption reduction, can benefit from improvements in aerodynamics and tires.

• Using the process and results from existing engine dynamometer testing for criteria emissions to certify fuel economy standards for MHDVs would build on proven accurate and repeatable methods and put less additional administrative burden on the industry. However, to account for the fuel consumption benefits of hybrid powertrains and transmission technology, the present engine-only tests for emissions certification will need to be augmented with other powertrain components added to the engine test cell, either as real hardware or simulated components. Similarly, the vehicle attributes (aero, tires, mass) will need to be accounted for, one approach being to use vehicle-specific prescribed loads (via models) in the test cycle. This will require close cooperation among component manufacturers and vehicle manufacturers.

Specific major recommendations of the report include:

• When NHTSA regulates, it should regulate the final-stage vehicle
  manufacturers since they have the greatest control over the design of the vehicle and its major subsystems that affect fuel consumption. Component manufacturers will have to provide
  consistent component performance data. As the components are generally tested at this time,
  there is a need for standardized test protocol and safe guards for the confidentiality of the data
  and information. It may be necessary for the vehicle manufacturers to provide the same level of
  data to the tier suppliers of the engines, transmissions, after-treatment and hybrid systems.

• Simulation modeling should be used with component test data and
  additional tested inputs from powertrain tests, which could lower the cost and administrative
  burden yet achieve the needed accuracy of results. This is similar to the approach taken by Japan,
  but with the important clarification that the program would represent all the parameters of the
  vehicle (powertrain, aerodynamics, and tires) and relate fuel consumption to the vehicle task.

• Congress should appropriate money and NHTSA should implement as
  soon as possible a major engineering contract that would take several actual vehicles covering
  several applications and develop the approach to component testing data in conjunction with
  vehicle simulation modeling to arrive at LSFC data for these vehicles. The actual vehicles should
  also be tested by appropriate full-scale test procedures to confirm the actual LSFC values and the
  reductions measured with fuel consumption reduction technologies in order to validate the
  evaluation method.

• NHTSA should conduct a pilot program to “test drive” the certification
  process and validate the regulatory instrument proof of concept.

While regulating medium- and heavy-duty vehicles will be more complicated than it is for passenger cars because of the variety of vehicles and their differing tasks and terrains, the barriers are not insurmountable, the report finds. Japan regulates the fuel economy of these vehicles, and both the European Union and the state of California are developing standards.

However, one way to avoid the complexity of regulating different types of vehicles would be to impose a fuel tax, which would induce firms to optimize the fuel-efficiency of their operations. The report urges Congress to consider this approach. Another alternative approach—applying a cap-and-trade system to trucking companies similar to the one that Congress is considering as a way to lower CO₂ emissions—would similarly provide these companies with an incentive to adopt fuel-saving technologies and operational methods.

In addition, the report recommends nontechnical methods NHTSA could use to lower fuel consumption, including providing incentives to train vehicle operators in efficient driving techniques, which can result in fuel savings of anywhere from 2-17%. One approach could be to establish a process to train and certify drivers in these techniques as part of commercial driver license certification.

In 2007 Congress passed legislation requiring the US Department of Transportation to establish the first fuel economy standards for medium- and heavy-duty vehicles. The National Highway Traffic Safety Administration asked the National Research Council to recommend the best ways to measure and regulate fuel economy for these vehicles, and assess technologies that could improve it.

The study was sponsored by the National Highway Traffic Safety Administration. The National Academy of Sciences, National Academy of Engineering, Institute of Medicine, and National Research Council make up the National Academies. They are private, nonprofit institutions that provide science, technology, and health policy advice under a congressional charter. The Research Council is the principal operating agency of the National Academy of Sciences and the National Academy of Engineering.

Resources

• Technologies and Approaches to Reducing the Fuel Consumption of Medium- and Heavy-Duty Vehicles