US. Department of Transportation National Highway Traffic Safety Administration DOT HS 806 971 May 1986 NHTSA Technical Report Fuel Economy and Annual Travel for Passenger Cars and Light Trucks: National On-Road Survey This document is available to the public from the National Technical Information Service, Springfield, Virginia 22161. Technical Report Documentation Page 1. Report No. 2. Government Accession No, 3. Recipient's Catalog No, DOT HS 806 971 4. Title and Subtitle 5, Report Date Fuel Economy and Annual Travel for Passenger Cars and May 1986 Light Trucks: National On-Road Survey 6. Performing Organization Code WPP-1 0 8. Performing Orgoniiotion Report No. 7. Author's) Glenn G. Parsons 9. Performing Organization Nome and Address 10. Work Unit No. (TRAIS) Office of Standards Evaluation National Highway Traffic Safety Administration 11. Controct or Grant No. 400 Seventh Street, S.W. Washington, DC 20590 13. Type of Report and Period Covered 12. Sponsoring Agency Name and Address U.S. Department of Transportation NHTSA Technical Report National Highway Traffic Safety Administration 400 Seventh Street, S.W. 14. Sponsoring Agency Code Washington, DC 20590 IS. Supplementary Notes An agency staff review of existing Federal regulations performed'in compliance with Executive Order 12291 and the agency's regulatory review plan (Regulatory Reform - The Review Process, DOT HS-806-159, March 1982). 16. Abstroet One of the principal actions taken by the United States in response tcr~tfte~ worldwide energy crisis of the 1970's was to Federally mandate minimum fuel economy standards for new motor vehicles. These standards began with the 1978 Model Year and continue in force today. This study is an assessment of the reduced energy (fuel) consumption for Model Year 1978-1981 vehicles, based on a national, on-road survey. In addition to the Federal standards, rapid rises in fuel costs in that period provided a second incentive for the production of more fuel efficient vehicles. The study found that: o From 1977 to 1981, on-road fuel economy of cars increased by 41 percent; for light trucks, from 1978 to 1981, the increase was 17-26 percent. o Fuel efficiency improvements in the 1978-1981 vehicles will reduce fuel consumption by 45.6 billion gallons—a dollar equivalent reduction of $53.8 billion. o On-road fuel economy is consistently below laboratory (EPA) ratings, ranging from 15-20 percent depending on vehicle type. o Average annual travel per vehicle is about 6,000 miles; both per vehicle and total fleet travel, based on odometer data, are markedly less than estimated by prior surveys. 17. Key Words 18, Distribution Statement Motor vehicle fuel economy, Federal fuel Document is available to the public economy standards, CAFE, on-road versus through the National Technical Information laboratory mpg, statistical survey, Service, Springfield, Virginia 22161 odometer readings, vehicle miles traveled 19. Security Classif. (of this report) 20. Security Classif. (of this page) 21* No. of Pages 22. Price Unclassified Unclassified 250 Form DOT F 1700.7 (8-72) Reproduction of completed page authorized i TABLE OF CONTENTS Acknowledgments. xi Executive Summary xiii CHAPTER 1 INTRODUCTION 1 CHAPTER 2 ANALYSIS OF SURVEY RESULTS OF FUEL ECONOMY AND ESTIMATION OF REDUCED ENERGY CONSUMPTION AND EQUIVALENT DOLLAR VALUE....10 2.1 Passenger Cars: On Road Fuel Economy 11 2.1.1 Reliability of On-Road Fuel Economy Estimates.... 15 2.1.2 On-Road Fuel Economy Versus CAFE ...18 2.1.3 On-Road Fuel Economy Compared to the Federal Standards 20 2.1.4 On-Road Fuel Economy by Size Class 21 2.1.5 On-Road Fuel Economy by Manufacturer 21 2.2 Light Trucks - Two-Wheel Drive: On-Road Fuel Economy 30 2.2.1 On-Road Fuel Economy Compared to EPA CAFE 34 2.2.2 On-Road Fuel Economy Compared to Federal Standard 36 2.3 Light Trucks - Four-Wheel Drive: On-Road Fuel Economy 37 2.4 Light Truck On-Road Fuel Economy by Size Class .39 2.5 Diesel izat ion 42 2.5.1 Effect of Dieselization on Fuel Economy 42 2.5.2 Diesel On-Road Fuel Economy Versus EPA Laboratory Estimates 45 2.6 Seasonal Effect on Fuel Economy 48 2.7 Comparison of ORFES Results with Prior Studies of on-Road Fuel Economy 52 2.7.1 Department of Energy Studies .52 2.7.2 Environmental Protection Agency Study 54 2.7.3 General Motors Study 55 2.7.4 Ford Motor Company Studies 57 2.7.5 Summary of ORFES Comparison with Other On-Road Fuel Economy Studies 59 iii 2.8 Estimated Reduction in Fuel Consumption and Equivalent Dollar Value 59 2.8.1 Reduced Fuel Consumption for Passenger Cars 60 2.8.2 Reduced Fuel Consumption for Light Trucks 69 2.8.3 Reduced Fuel Consumption, Light Vehicle Fleet....73 2.8.4 Discussion of Reduced Fuel Consumption and Dollar Equivalent Estimates ....75 CHAPTER 3 ANALYSIS OF SURVEY RESULTS OF VEHICLE MILES TRAVELED 78 3.1 Methodology for Estimating Vehicle Miles Traveled 79 3.2 Vehicle Miles Traveled Estimates 83 3.2.1 Overall Estimates by Model Year and Vehicle Type 83 3.2.2 Estimates by Size Class 90 3.2.3 Estimates by Type of Fuel 94 3.2.4 Annual VMT Estimates 97 3.2.5 Comparison of ORFES VMT Estimates with Other Survey Estimates 108 CHAPTER 4 SURVEY METHODOLOGY AND DATA COLLECTION 115 4.1 Survey Design 116 4.1.1 Target Population and Sampling Frame 116 4.1.2 Sample Selection, Stratification, and Division into Replicates 119 4.2 Questionnaire Design and Data Collection Methodology... 123 4.3 Data Collection, Processing, and Statistical Estimation ....128 4.3.1 Receipt Control 128 4.3.2 Data Processing 130 4.3.3 Statistical Estimation 133 4.4 Survey Response and Nonresponse Issues 136 4.5 Potential Sources of Error in ORFES Statistics 140 4.5.1 Sampling Error 140 4.5.2 Nonsampling Error 141 iv CHAPTER 5 PRINCIPAL SURVEY FINDINGS AND RESULTS 148 5.1 On-Road Fuel Economy Results - Passenger Cars 148 5.2 On-Road Fuel Economy Results - Light Trucks 149 5.3 On-Road Fuel Economy Compared to CAFE 151 5.4 On-Road Fuel Economy Compared to Federal Standards..... 152 5.5 Estimated Reduction in Energy Consumption and Equivalent Dollar Value of More Fuel-Efficient Vehicles 153 5.6 Estimates of Vehicle Miles Traveled 153 REFERENCES 157 APPENDIX A Listing of Vehicle Make Models Sampled in ORFES 160 APPENDIX B Estimation of Average Vehicle Age .< 202 APPENDIX C Survey Support Materials 205 (Prenotification Letter - NHTSA) 206 (Prenotification Letter - Survey Contractor) 207 (Questionnaire Transmittal Letter - First Wave). 208 (Incentive Log Booklet) 209 (Decals) 210 (Reminder Postcards) 211 (Questionnaire Transmittal Letter - Second Wave) 212 (Telephone Questionnaire) 213 (Questionnaire Transmittal Letter - Telephone Followup)... .217 APPENDIX D Methodology and Data for Estimating Reduced Energy Consumption and Equivalent Dollar Value 228 LIST OF TABLES Table 1-1 "Fuel Economy Standards for Passenger Cars and Light Trucks for the 1978 through 1987 Model Years (in MPG) 3 Table 2-1 Passenger Car On-Road Fuel Economy and Comparison to CAFE, Domestic and Import Fleets 12 Table 2-2 Standard Error and 95 Percent Confidence Intervals for Passenger Car On-Road MPG .' 17 Table 2-3 Passenger Cars: Comparison of On-R-oad Fuel Economy with CAFE and with Fuel Economy Standards 19 Table 2-4 Passenger Car On-Road Fuel Economy, Size Class by Model Year 22 Table 2-5 Passenger Car On-Road Fuel Economy by Manufacturer (Domestic) and Model Year.. 23 Table 2-6 Import Passenger Car Fleet - On-Road MPG by Manufacturer and Model Year 24 Table 2-7 Domestic Passenger Car Fleet - Comparison of On-Road MPG with CAFE, by Manufacturer 26 Table 2-8 Domestic Passenger Car Fleet - Comparison of On-Road MPG with Federal Standard, by Manufacturer..... 27 Table 2-9 Import Passenger Car Fleet - Comparison of On-Road MPG with CAFE, by Manufacturer 29 Table 2-10 Import Passenger Car Fleet -. Comparison of On-Road MPG with Federal Standard Levels 31 Table 2-11 Light Truck On-Road Fuel Economy and Comparisons to Cafe, Domestic and Import Fleets 32 Table 2-12 Light Truck: Two-Wheel Drive - Comparison of On-Road Fuel Economy with CAFE and with Fuel Economy Standards 35 Table 2-13 Light Truck: Four-Wheel Drive - Comparison of On-Road Fuel Economy with CAFE and with Federal Standards 38 Table 2-14 Light Truck On-Road Fuel Economy - Size Class by Model Year 41 Table 2-15 Comparison of Fuel Economy (MPG) between Diesel and Gasoline Powered Vehicles 43 Table 2-16 Diesel On-Road Fuel Economy Versus EPA Laboratory Estimates: 1981 Passenger Cars 47 vi Table 2-17 On-Road Fuel Economy by Season of Year (Passenger Cars Plus Light Trucks) 50 Table 2-18 Calendar Year Sales of Light Trucks, Model Years 1979-1981...69 Table 2-19(a) Total Reduction in Fuel Consumption and Dollar Equivalent Value - Passenger Cars and Light Trucks, 74 Table 2-19(b) Per Vehicle Reduction in Fuel Consumption and Dollar Equivalent Value - Passenger Cars and Light Trucks 74 Table 3-1 Total Average Vehicle Miles Traveled, as of July 1, 1983, by Type of Vehicle and Model Year 83 Table 3-2 Standard Deviation and Standard Errors for VMT Estimates 85 Table 3-3 Ninety-five Percent Confidence Limits and Tolerance Limits on VMT by Vehicle Model Year 88 Table 3-4 Total Vehicle Miles Traveled, Passenger Cars by Size Class....91 Table 3-5 Total Vehicle Miles Traveled, Light Trucks by Size Class 92 Table 3-6 Average VMT Rank by Size Class, Passenger Cars 93 Table 3-7 Vehicle Miles Traveled - Passenger Cars, Gasoline Versus Diesel 95 Table 3-8 Total Vehicle Miles Traveled, Gasoline Versus Diesel, Light Trucks 96 Table 3-9 Comparison of Observed and Predicted VMT 102 Table 3-10 Cumulative and Annual VMT Estimates Based on Fitted Logarithmic Curve 105 Table 3-11 Data for Computation of Average Annual VMT, Entire U.S.