accuracy. This proposed method would determine a characteristic vehicle that would be defined as a reasonable average representative of a class of vehicles. This representative vehicle, whether real or theoretical, would undergo sufficient FSS, combined with experimentally determined and vehicle-class-specific system mapping, to allow a reasonable understanding of the contributory effects of the technologies applied to reduce vehicle energy losses. Data developed under the United States Council for Automotive Research ( USCAR) Benchmarking Consortium should be considered as a source for such analysis and potentially expanded. Under the USCAR program, actual production vehicles are subjected to a battery of vehicle, engine, and transmission tests in sufficient detail to understand how each candidate technology is applied and how it contributes to the overall performance and fuel consumption of light-duty vehicles. Combining the results of such testing with FSS modeling, and thereby making all simulation variables and subsystem maps transparent to all interested parties, would allow the best opportunity to define a technical baseline against which potential improvements could be analyzed more accurately and openly than is the case with the current methods employed.

The steps in the recommended process are as follows:

  1. Develop a set of baseline vehicle classes from which a characteristic vehicle can be chosen to represent each class. The vehicle may be either real or theoretical and will possess the average attributes of that class as determined by sales-weighted averages.

  2. Identify technologies with a potential to reduce fuel consumption.

  3. Determine the applicability of each technology to the various vehicle classes.

  4. Estimate each technology’s preliminary impact on fuel consumption and cost.

  5. Determine the optimum implementation sequence (technology pathway) based on cost-effectiveness and engineering considerations.

  6. Document the cost-effectiveness and engineering judgment assumptions used in step 5 and make this information part of a widely accessible database.

  7. Utilize modeling software (FSS) to progress through each technology pathway for each vehicle class to obtain the final incremental effects of adding each technology.

If such a process were adopted as part of a regulatory rulemaking procedure, it could be completed on 3-year cycles to allow regulatory agencies sufficient lead time to integrate the results into future proposed and enacted rules.


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EPA. 2008b. EPA Staff Technical Report: Cost and Effectiveness Estimates of Technologies Used to Reduce Light-Duty Vehicle Carbon Dioxide Emissions. EPA420-R-08-008. Ann Arbor, Mich.

NHTSA (National Highway Traffic Safety Administration). 2009. Average fuel economy standards, passenger cars and light trucks, model-year 2011: final rule, RIN 2127 AK-29, Docket No. NHTSA 2009-0062. Washington, D.C., March 23.

NRC (National Research Council). 2002. Effectiveness and Impact of Corporate Average Fuel Economy (CAFE) Standards. National Academy Press, Washington, D.C.

Ricardo, Inc. 2008. A Study of Potential Effectiveness of Carbon Dioxide Reducing Vehicle Technologies. EPA420-R-08-004. Prepared for the U.S. Environmental Protection Agency, Contract No. EP-C-06-003, Work Assignment No. 1-14. Ann Arbor, Mich.

Ricardo, Inc. 2009. A Study of Interaction Effects Between Light Duty Vehicle Technologies. Prepared for the NRC Committee on Assessment of Technologies for Improving Light-Duty Vehicle Fuel Economy by Ricardo Inc., Van Buren, Mich., February 27.

Sovran, G., and M.S. Bohn. 1981. Formulae for the tractive energy requirements of vehicles driving the EPA schedule, SAE Paper 810184. February.

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