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Title: Analysis of In-Use Fuel Economy Shortfall Based on Voluntarily Reported MPG Estimates

Abstract

The usefulness of the Environmental Protection Agency's (EPA) passenger car and light truck fuel economy estimates has been the subject of debate for the past three decades. For the labels on new vehicles and the fuel economy information given to the public, the EPA adjusts dynamometer test results downward by 10% for the city cycle and 22% for the highway cycle to better reflect real world driving conditions. These adjustment factors were developed in 1984 and their continued validity has repeatedly been questioned. In March of 2005 the U.S. Department of Energy (DOE) and EPA's fuel economy information website, www.fueleconomy.gov, began allowing users to voluntarily share fuel economy estimates. This paper presents an initial statistical analysis of more than 3,000 estimates submitted by website users. The analysis suggests two potentially important results: (1) adjusted, combined EPA fuel economy estimates appear to be approximately unbiased estimators of the average fuel economy consumers will experience in actual driving, and (2) the EPA estimates are highly imprecise predictors of any given individual's in-use fuel economy, an approximate 95% confidence interval being +/-7 MPG. These results imply that what is needed is not less biased adjustment factors for the EPA estimates but rather moremore » precise methods of predicting the fuel economy individual consumers will achieve in their own driving.« less

Authors:
 [1];  [1];  [2];  [1]
  1. ORNL
  2. University of Tennessee, Knoxville (UTK)
Publication Date:
Research Org.:
Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
Sponsoring Org.:
USDOE Office of Energy Efficiency and Renewable Energy (EERE)
OSTI Identifier:
931042
DOE Contract Number:  
DE-AC05-00OR22725
Resource Type:
Conference
Resource Relation:
Conference: Transportation Research Board's Annual Meeting, Washington, DC, USA, 20060122, 20060126
Country of Publication:
United States
Language:
English
Subject:
32 ENERGY CONSERVATION, CONSUMPTION, AND UTILIZATION; AUTOMOBILES; DYNAMOMETERS; FUEL CONSUMPTION; TRUCKS; US EPA; DATA ANALYSIS

Citation Formats

Greene, David L, Goeltz, Rick, Hopson, Dr Janet L, and Tworek, Elzbieta. Analysis of In-Use Fuel Economy Shortfall Based on Voluntarily Reported MPG Estimates. United States: N. p., 2007. Web.
Greene, David L, Goeltz, Rick, Hopson, Dr Janet L, & Tworek, Elzbieta. Analysis of In-Use Fuel Economy Shortfall Based on Voluntarily Reported MPG Estimates. United States.
Greene, David L, Goeltz, Rick, Hopson, Dr Janet L, and Tworek, Elzbieta. Mon . "Analysis of In-Use Fuel Economy Shortfall Based on Voluntarily Reported MPG Estimates". United States. doi:.
@article{osti_931042,
title = {Analysis of In-Use Fuel Economy Shortfall Based on Voluntarily Reported MPG Estimates},
author = {Greene, David L and Goeltz, Rick and Hopson, Dr Janet L and Tworek, Elzbieta},
abstractNote = {The usefulness of the Environmental Protection Agency's (EPA) passenger car and light truck fuel economy estimates has been the subject of debate for the past three decades. For the labels on new vehicles and the fuel economy information given to the public, the EPA adjusts dynamometer test results downward by 10% for the city cycle and 22% for the highway cycle to better reflect real world driving conditions. These adjustment factors were developed in 1984 and their continued validity has repeatedly been questioned. In March of 2005 the U.S. Department of Energy (DOE) and EPA's fuel economy information website, www.fueleconomy.gov, began allowing users to voluntarily share fuel economy estimates. This paper presents an initial statistical analysis of more than 3,000 estimates submitted by website users. The analysis suggests two potentially important results: (1) adjusted, combined EPA fuel economy estimates appear to be approximately unbiased estimators of the average fuel economy consumers will experience in actual driving, and (2) the EPA estimates are highly imprecise predictors of any given individual's in-use fuel economy, an approximate 95% confidence interval being +/-7 MPG. These results imply that what is needed is not less biased adjustment factors for the EPA estimates but rather more precise methods of predicting the fuel economy individual consumers will achieve in their own driving.},
doi = {},
journal = {},
number = ,
volume = ,
place = {United States},
year = {Mon Jan 01 00:00:00 EST 2007},
month = {Mon Jan 01 00:00:00 EST 2007}
}

Conference:
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