Study Finds That Tripling US LDV New Fleet Fuel Efficiency by 2035 Through Evolutionary Change is Ambitious But Doable

New fleet efficiency horizon in terms of energy intensity and fuel consumption rate compared to historical fleet averages and recent US regulations. Source: DeCicco 2010. Click to enlarge.

Tripling US new light-duty vehicle fleet fuel efficiency by 2035 through evolutionary change—e.g., relying heavily on improvements in advanced engines and in the application of hybrid drive technology—rather than on revolutionary alternatives such as plug-in vehicles or hydrogen requiring extensive new infrastructure is an “ambitious but defensible horizonaccording to a new study by John DeCicco, a senior lecturer at the University of Michigan’s School of Natural Resources and Environment and faculty fellow.

DeCicco’s analysis shows that optimizing internal combustion engines plus rising adoption of grid-free hybrids will enable new fleet fuel economy (unadjusted) to reach 52 mpg (4.52 L/100km) by 2025 and 74 mpg (3.18 L/100km) by 2035. Adjusted on-road fuel economy correspondingly would be 41 mpg (5.74 L/100km) and 60 mpg (3.92 L/100km). CO2 emissions, with AC, would reach 104 g/mi in 2035. The study, “A Fuel Efficiency Horizon for US Automobiles”, was prepared for The Energy Foundation.

Reaching [this horizon] will entail rising costs that are best seen as opportunity costs for features that might otherwise appear in cars if high fuel efficiency levels are not sought. Achieving this horizon at the costs projected means foregoing further gains in average acceleration performance, a marked departure from past trends. If instead performance rises in line with its historical trend, the 2035 horizon drops from tripled down to roughly doubled fuel efficiency. Nevertheless, improving the fleet toward such a horizon through evolutionary change remains less costly than “revolutionary” alternatives requiring extensive new infrastructure. In short, attaining or even approaching the fuel efficiency horizon projected here will yield substantial benefits for reducing oil consumption and limiting GHG emissions from the transportation sector.

—A Fuel Efficiency Horizon for US Automobiles

The study examines how far automobile efficiency can be taken if it is pursued with determination, using an analysis that assumes success in technology and design strategies that offer “revolution by evolution.” The study does not perform new detailed engineering analysis, but rather synthesizes published results under an assumption that efficiency gains from evolutionary technology changes are maximized on a fleetwide basis.

Many analyses highlight alternative technologies for replacing internal combustion engines and petroleum-based fuels, such as grid-based vehicle electrification, biofuels, hydrogen or natural gas. Others point to radical changes in vehicle materials and design. Proponents of these options marshal technological optimism in scenarios that show how their alternatives will revolutionize the automobile. While such options mature, it will be crucial to pursue evolutionary advances in existing systems, which can be greatly improved at cost, but at much less cost and with none of the other barriers faced by alternative technologies.

—A Fuel Efficiency Horizon for US Automobiles

DeCicco says that the rate of technology progress, particularly for the degree of hybridization likely to be needed, he assumes are in line with those of some major automotive technology changes in the past; the challenge is cost, which rises steadily as greater use of advanced technology is required.

Nevertheless, projected fuel savings greatly exceed upfront costs and this evolutionary horizon remains less costly than revolutionary changes in vehicles based on electric grid connection, hydrogen or other alternatives that entail extensive new infrastructure. As interpreted here, however, these options are used only as an existence proof of the potential for high fuel efficiency rather than as a literal technology pathway to be implemented. Thus, the view is technologically agnostic and reflects opportunities identified through engineering fundamentals.

—A Fuel Efficiency Horizon for US Automobiles

To entice buyers away from a focus on power, and toward smart technology, DeCicco identifies emerging trends for what he dubs efficiency compatible design strategies. Amenities like Bluetooth hookups, communication bandwidth and other information technology enhance customer value with minimal demands on power.

Compatible strategies are approaches for both individual vehicles and product plans that enhance customer value by emphasizing features that are not inherently fuel consumptive. Such options include intelligent systems content, matching performance to real world driving needs, creative downsizing, interior packaging and styling—in short, appealing to consumers in ways that are in line with, as opposed to work against, fuel efficiency.

—A Fuel Efficiency Horizon for US Automobiles

The report develops new interpretations of technology cost estimates that better depict the benefits of ongoing innovation while acknowledging the limits of how much consumers can spend. The analysis reflects the three-way trade-off among efficiency, performance and cost that the car market is likely to face in the years ahead.

The fleet I’ve modeled for 2025 does not give up any of the performance and creature comforts consumers already enjoy. You don’t have to go back to being Fred Flintstone, but you will see lower fuel costs instead of ever more mass and muscle.

—John DeCicco


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