NRC report finds Federal analysis to set LD CAFE and GHG standards generally of high quality; some technologies and issues should be re-examined
19 June 2015
The analysis used by federal agencies to set standards for fuel economy (CAFE) and greenhouse gas emissions for new US light-duty vehicles from 2017 to 2025 was thorough and of high caliber overall, according to a new report from the National Research Council.
However, the report authors found, the agencies should re-examine certain issues such as consumer behavior and the effectiveness of certain technologies in an upcoming mid-term review. In addition, the report found, evidence suggests that the standards will lead the nation’s light-duty vehicle fleet to become lighter but not less safe.
Background. In 2012 the US National Highway Traffic Safety Administration (NHTSA), which regulates fuel economy, and the US Environmental Protection Agency (EPA), which regulates greenhouse gas emissions, proposed new unified standards for fuel economy and greenhouse gas emissions over the years 2017 to 2025. The Corporate Average Fuel Economy (CAFE) standards require that vehicles offered for sale in the US attain an average fuel economy of 40.3 to 41 mpg by 2021 and 48.7 to 49.7 mpg by 2025. These standards will require the US new vehicle fleet to double in fuel economy between 2012 and 2025.
Under the Energy Independence and Security Act of 2007, NHTSA does not have the statutory authority for setting CAFE standards for more than five years at a time—i.e., only the MY 2017-2021 CAFE standards are final. Beginning in 2016, NHTSA and EPA will coordinate a mid-term review that must be finalized by April 2018.
In conjunction with EPA and the California Air Resources Board (ARB), NHTSA will perform a joint technical analysis as part of its rulemaking for the MY 2022-2025 standards. The NRC study is intended to feed into the mid-term review and provide an independent review of technologies and the CAFE program more generally.
The National Research Council is the principal operating arm of the National Academy of Sciences and the National Academy of Engineering.
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| UMTRI Survey: US drivers want better fuel economy, don’t care how |
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| In a new survey of 674 vehicle owners across the country, Brandon Schoettle and Dr. Michael Sivak of the University of Michigan Transportation Research Institute (UMTRI) examined several topics related to fuel economy and advanced vehicle technologies. |
| 52% of respondents said it didn’t matter to them how a vehicle saves fuel and reduces emissions. However, 24% listed engine improvements and 20% cited alternative fuels as their preference for improving fuel economy. |
| Men and drivers over 45 were more likely to favor engine improvements, while younger motorists preferred alternative fuel sources (diesel, electric, hydrogen) as the primary means to save fuel and reduce emissions. |
| About 73% of those surveyed said they would be less likely to own or lease a vehicle that requires more expensive premium fuel. |
| While about 90% of respondents indicated that they basically understand how diesel engines and gasoline-hybrid vehicles work, a majority also said they had never heard of twincharging, cylinder deactivation or continuously variable transmissions. |
| Stop-start engine systems received the most negative ratings, although more than 60% of respondents viewed them as at least somewhat positive. |
| The U-M survey also asked vehicle owners which advanced technology they would prefer at two different gasoline price points: $2.50/gallon and $5/gallon. At both prices, gasoline-hybrid vehicles were the most preferred technology, while twincharging was the least. |
| Among powertrains, gasoline hybrids ranked first at either price point, while diesel internal-combustion engines were the least preferred. Gasoline internal-combustion engines rated second-most preferred at $2.50/gallon, ahead of electric vehicles, plug-in hybrids and hydrogen fuel-cell vehicles—but below them at the higher price point. |
| Finally, Schoettle and Sivak asked respondents about their willingness to pay for improved fuel economy. The results indicate that 25% would be willing to pay at least $300 for a 5% improvement in fuel economy; $1,000 for a 10% improvement and $2,500 for a 25% improvement. |
Summary findings. The NRC committee’s report discussed a wide range of technologies and opportunities for reducing fuel consumption in light-duty vehicles. The committee found the analysis conducted by NHTSA and EPA in their development of the 2017-2025 standards “to be thorough and of high caliber on the whole.”
The increasingly stringent fuel economy and greenhouse gas emission standards will drive the development of new powertrain designs, alternative fuels, advanced materials, and significant changes to the vehicle body, the report says. By the end of the next decade, because of the standards and other regulations, new vehicles will be more fuel-efficient, lighter, less polluting, safer, and more expensive to purchase compared with current vehicles.
Most of the reduction in fuel consumption will come from improvements to gasoline internal combustion engines, due to the continuing dominance of such technologies through 2025, the report says. However, the study committee that wrote the report considered a wide range of technologies to be critical in meeting the 2025 standards and beyond, including improvements to transmissions, reductions in mass, and hybrid/electric engines.
As part of the analysis used to set CAFE and greenhouse gas standards, NHTSA and EPA estimated the fuel economy improvements that could be generated by various technologies available between 2017 and 2025, as well as the costs of implementing those technologies. The report concurs with the agencies’ costs and effectiveness analyses for many technologies. However, in some cases its estimates significantly differed from the agencies’; NHTSA and EPA should pay particular attention to re-analyzing these technologies during the mid-term review.
For example, the report finds that auto manufacturers are likely to reduce the weight of vehicles more than NHTSA and EPA’s analysis indicates, leading to both greater fuel economy benefits and greater costs than the agencies estimate. In addition, deploying turbocharged, downsized engines—which are expected to replace many current engines—may cost more and produce less fuel savings than the agencies’ analysis indicates.
Recommendations. The report authors made recommendations in a number of areas, including:
Estimated Fuel Consumption Reductions and Cost. While the committee concurred with the costs and effectiveness values for a wide array of technologies, in some cases the committee developed estimates that significantly differed from the Agencies’ values. The committee recommended that the Agencies pay particular attention to the reanalysis of these technologies in the mid-term review.
The committee also recommended the Agencies establish a new definition of a “null” vehicle, representative of the most basic vehicle in the 2016 MY time frame as well as a baseline 2016 MY fleet reflecting actual technology penetration rates. This will assist in distinguishing between technologies available for the MY 2017-2025 CAFE targets and technologies that have already been applied to reach the MY 2016 CAFE targets.
Further, the committee noted that the use of full vehicle simulation modeling in combination with lumped parameter modeling and tear-down studies contributed substantially to the value of the Agencies’ estimates of fuel consumption and costs, and it recommends they continue to increase the use of these methods to improve their analysis.
Spark-Ignition Engines. Since spark-ignition engines are expected to be dominant beyond 2025, updated effectiveness and cost estimates of the most effective spark-ignition engine technologies should be developed for the mid-term review of the CAFE standards.
Updated effectiveness estimates should be derived from full system simulations using engine maps based on measured data or generated engine model maps derived from validated baselines and include models for fuel octane requirements and drivability. Updated cost estimates using teardown cost studies of recently introduced spark-ignition engine technologies, including all vehicle integration costs, should be developed to support the mid-term review.
- Compression-Ignition Engines. EPA and NHTSA should expand their full system simulations supported by mapping the latest diesel engines that incorporates as many of the latest technologies as possible. EPA and NHTSA should conduct a teardown cost study of a modern diesel engine with the latest technologies to provide an up-to-date estimate of diesel engine costs. The teardown study should evaluate all costs, including vehicle integration, which includes the cooling system, torsional vibration damper, electrical systems, including starter motors, batteries and alternator, noise, vibration, and harshness (NVH) control technologies, and vehicle costs resulting from the increased weight of the diesel engine. The study should include an analysis of the increased residual value of a diesel-powered vehicle.
Hybrid and Electrified Powertrains. For their mid-term review, the Agencies should examine auto manufacturer’s experiences of battery life to determine the appropriate state of charge swing for PHEVs and BEVs so that they can assign costs appropriately. The Agencies should undertake a teardown of the next generation PS and P2 architectures to update cost and full system simulation of P2 and PS architectures to update cost.
Further, at the time of the mid-term review, there will be several vehicles with electrified powertrains in the market. The Agencies should commission teardown studies of the most successful examples of (1) stop-start, (2) strong hybrids (PS, P2, and two motor architectures), (3) PHEV20 and PHEV40, and (4) BEV100. At that time there will be better estimates of volumes for each type in the 2020 to 2025 time frame so that a better estimate of cost can be calculated.
Transmissions. NHTSA and EPA should add the CVT to the list of technologies applicable for the 2017-2025 CAFE standards. NHTSA and EPA should update the analyses of technology penetration rates for the midterm review to reflect the anticipated low DCT penetration rate in the US market.
Non-Powertrain Technologies. The committee recommended that the Agencies augment their current work with a materials-based approach that looks across the fleet to better define opportunities and costs for implementing lightweighting techniques, especially in the area of decompounding. A characterization of current vehicles in terms of materials content is a prerequisite for such a materials-based approach and for quantifying the opportunities to incorporate different lightweighting materials in the fleet.
Cost and Manufacturing Considerations. The Agencies should continue research on indirect cost multipliers with the goal of developing a sound empirical basis for their estimation. The Agencies should continue to conduct and review empirical evidence for the cost reductions that occur in the automobile industry with volume, especially for large volume technologies that will be relied on to meet the CAFE/GHG standards.
Consumer Impacts and Acceptance Issues. The committee recommended that the Agencies do more research on the existence and extent of the energy paradox in fuel economy, the reasons for consumers’ undervaluation of fuel economy relative to its discounted expected present value, and differences in consumers’ perceptions across the population. The Agencies should study the value of vehicle attributes to consumers, consumer willingness to trade off other attributes for fuel economy, and the likelihood of consumer adoption of new, unfamiliar technologies in the vehicle market.
The Agencies should also conduct more research on the existence and extent of supply-side barriers to long-term investments in fuel economy technologies.
Assessment of CAFE Program Methodology and Design. The Agencies should monitor the effects of the CAFE/GHG standards by collecting data on fuel efficiency, vehicle footprint, fleet size mix, and price of new vehicles to understand the impact of the rules on consumers’ choices and manufacturers’ products offered.
The Agencies, perhaps in collaboration with other federal agencies, should conduct an on-going, scientifically-designed survey of the real-world fuel economy of light-duty vehicles. The survey should also collect information on real-world driving behavior and driving cycles. This information will be useful in determining the adequacy of the current test cycle and could inform the establishment of improved, future (post-2025) test cycles, if necessary.
The Agencies should consider how to develop a reference case for the analysis of societal costs and benefits that includes accounting for the potential opportunity costs of the standards in terms of alternative vehicle attributes forgone. The midterm review is a time that the Agencies should consider how the credit markets are different between the CAFE and GHG rules, and what the implications of these differences are for the auto manufacturers.
Further, the committee recommends that the Agencies study the potential benefits, costs and risks of establishing a standard based on a single metric that achieves both GHG and petroleum reductions in addition to continued efforts to harmonize the two regulations. Permanent regulatory treatment of alternate-fuel vehicles (AFVs) should be commensurate with the well-to-wheels GHG and petroleum reduction benefits.
Resources
National Research Council. Cost, Effectiveness and Deployment of Fuel Economy Technologies for Light-Duty Vehicles. Washington, DC: The National Academies Press, 2015.
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