Assessment of Fuel Economy Technologies for Light-Duty Vehicles (2011)

The committee formed to carry out this study will provide updated estimates of the cost and potential efficiency improvements of technologies that might be employed over the next 15 years to increase the fuel economy of various light-duty vehicle classes. Specifically, the committee shall:

1. Reassess the technologies analyzed in Chapter 3 of the NRC report, Impact and Effectiveness of Corporate Average Fuel Economy (CAFE) Standards (2002), for efficacy, cost, and applicability to the classes of vehicles considered in that report. In addition, technologies that were noted but not analyzed in depth in that report, including direct injection engines, diesel engines, and hybrid electric vehicles, shall be assessed for efficacy, cost and applicability. Weight and power reductions also shall be included, though consideration of weight reductions should be limited to advances in structural design and lightweight materials. The assessments shall include the effects of “technology sequencing”—in what order manufacturers might conceivably incorporate fuel economy technologies, and how such ordering affects technology cost and applicability.

2. Estimate the efficacy, cost, and applicability of emerging fuel economy technologies that might be employed over the next 15 years. The assessments shall include the effects of technology sequencing as defined in (1) above.

3. Identify and assess leading computer models for projecting vehicle fuel economy as a function of additional technology. These models would include both:

   • Lumped parameter (or Partial Discrete Approximation) type models, where interactions among technologies are represented using energy partitioning and/or scalar adjustment factors (also known as synergy factors), and

   • Full vehicle simulation, in which such interactions are analyzed using explicit drive cycle and engine cycle simulation, based on detailed vehicle engineering characteristics (e.g., including engine maps, transmission shift points, etc.).

4. Check the models against current, known fuel economy examples and select one of each type to perform the analyses of the effects of the technologies in 1 and 2 above.

5. Develop a set of cost/potential efficiency improvement curves, as in Chapter 3 of the 2002 NRC report, that is guided by the following question: “What is the estimated cost and potential fuel economy benefit of technologies that could be applied to improve the fuel economy of future passenger vehicles, given the constraints imposed by vehicle performance, functionality, safety and emission regulations?” The ten vehicle classes considered in the 2002 report shall be analyzed, including important variants such as different engine sizes (e.g., 6 and 8 cylinders). Most analyses shall be performed with the lumped parameter model, but sufficient cases to ensure overall accuracy shall be checked with the engine mapping model.

6. Define and document the specific methodology(ies) and inputs used to estimate the incremental costs and benefits of the fuel economy technologies chosen by the committee, including the methods used to account for variations in vehicle characteristics (e.g., size, weight, engine characteristics) and to account for the sequential application of technologies. Use flow charts or similar methods to document sequencing upon which the committee’s estimates of incremental costs and benefits are based. Although methodologies vary, the committee’s report should detail all of its calculation methodology(ies), even those as basic as simple mathematical relationships (if used) and as complex as structural representations, such as decision trees (if used). It should do so to levels of specificity, clarity and completeness sufficient for implementation and inte-

gration into models that project the fuel economy capability of vehicles, fleets and manufacturers, including fleets specified at the level of individual vehicle models, engines, and transmissions. The report should also provide and document estimates of all input data required for implementation of these methodologies.

1. Assess how ongoing changes to manufacturers’ refresh and redesign cycles for vehicle models affect the incorporation of new fuel-economy technologies.

The committee’s analysis and methodologies will be documented in two NRC-approved reports. An interim report will discuss the technologies to be analyzed, the classes of vehicles which may employ them, the estimated improvement in fuel economy that may result, and the models that will be used for analysis. The final report will include the detailed specifications for the methodologies used and the results of the modeling, and will make use of the input from the interim report and any new information that is available.