____________________________________________________________________________ This document is available to the public from the Nationa l Technical Information Servic e, Springfield, VA 22161 DOT HS 809 952 January 2006

Technical Report



# V EHICLE 

# S URVIVABILITY


# A ND


# T RAVEL 

# M ILEAGE 

# S CHEDULES

Published By: NHTSA’s National Center for Statistics and AnalysisTechnical Report Documentation Page

1. Report No. DOT HS 809 952 2. Government Accession No. 3. Recipients's Catalog No.

5. Report Date January, 2006 4. Title and Subtitle

Vehicle Survivability and Travel Mileage Schedules 6. Performing Organization Code NPO-130

7. Author(s) S. Lu 8. Performing Organization Report No.

10. Work Unit No. (TRAIS)n code 9. Performing Organization Name and Address

National Center for Statistics and Analysis Regulatory Analysis and Evaluation Division National Highway Traffic Safety Administration U.S. Department of Transportation NPO-130, 400 Seventh Street, S.W. Washington, DC 20590 11. Contract of Grant No.

13. Type of Report and Period Covered NHTSA Technical Report 12. Sponsoring Agency Name and Address

U.S. Department of Transportation
NPO-130, 400 Seventh Street, S.W.
Washington, DC 20590 14. Sponsoring Agency Code

15.Supplementary Notes

16. Abstract

This document serves to update the 1995 document of the same title. In this revision, we attempt to retain the methodology as much as possible from the previous rele ase. Regardless, some ch anges were introduced in this updated analysis when needed. In this revision, we find that passenger cars and light trucks are being driven farther in their lifetimes (approximately 26,000 miles more per vehicle cl ass). However, whereas younger passenger cars (less than 20 years old) are surv iving slightly longer relati ve to the previous study, light trucks are not surviving as long as before early on in their existen ce, presumably due to the fact that they are being used more often as passeng er vehicles than strictly for cargo.

The updated analysis shows that a typical passenger ca r will travel a lifetime m ileage of 152,137 miles, while light trucks will travel 179,954 miles. Passenger car lifetime weighted presen t discount factors at 3 percent, 7 percent and 10 percent are, resp ectively, 0.8304, 0.6700 and 0.5824; for light tr ucks with the same discount rates, respectively, 0.8022, 0.6303 and 0.5419.

17. Key Words VMT, vehicle miles traveled, survival rate, survivability, discount factors, lifetime vehicle mileage 18. Distribution Statement Document is available to the public through the National Technical Information Service, Springfield, VA 22161

19. Security Classif. (of this report) Unclassified 20. Security Classif. (of this page) Unclassified 21. No of Pages 40 (including title page) 22. Price

Form DOT F1700.7 (8-72) Reproduction of completed page authorizediii Table of Contents

Executive Summary ____________________________________________________ 1

1. Introduction of Current Survivability and VMT Schedules _________________ 2

1.1. Passenger Cars ___________________________________________________ 2

1.2. Light Trucks _____________________________________________________ 2

2. Data Sources________________________________________________________ 5

3. Survivability Analysis ________________________________________________ 6

3.1. Passenger Cars ___________________________________________________ 6

3.2 Light Trucks _____________________________________________________ 10

4. VMT Analysis______________________________________________________ 13

4.1. Passenger Cars __________________________________________________ 14

4.2. Light Trucks ____________________________________________________ 17

5. Lifetime Mileage____________________________________________________ 21

5.1. Passenger Cars __________________________________________________ 21

5.2. Light Trucks ____________________________________________________ 24

6. Discount Factors____________________________________________________ 27

7. Appendix__________________________________________________________ 34

7.1. Corporate Average Fuel Economy (CAFE) VMT Schedules _______________ 351 Executive Summary

Vehicle survivability and vehicle miles travel ed (VMT) schedules for passenger cars and light trucks were develope d from 1977 to 2002 registration and 2001 mileage survey data. Compared to similar projections ma de in 1995, we found that passenger cars are lasting longer whereas light trucks are not lasting as long. However, both are being driven slightly farther than pr evious schedules had indicated.

In this analysis, vehicle age was cut off fo r passenger cars and light trucks when the Estimated Survival Rate reached an approxi mately two percent threshold. Thus, the lifetime VMT of passenger cars was extended to 25 years to arrive at 152,137 miles; and the lifetime VMT of light trucks was extende d to 36 years to arrive at 179,954 miles.
Previous lifetime VMT estimates were 126,665 for passenger cars (20 years) and 153,698 (25 years) for light trucks. Discount fact ors are also updated in this analysis and summarized below along with the lifetime mileage.

Lifetime Weighted Present Discount Factor Lifetime Mileage 3% 7% 10% Passenger Car 152,137 0.8304 0.6700 0.5824 Light Truck 179,954 0.8022 0.6303 0.5419

These updated schedules should be used to as sess the effects of proposed fuel economy and safety standards.2 1. Introduction of Current Survivability and VMT Schedules

Survivability and vehicle mileage by age schedules are needed to accurately assess the impact of automotive fuel economy standards and safety standards. The survivability schedule can be used to estimate the phase-in of new safety equipment into the vehicle fleet. These two schedules are used to comput e the total weighted travel mileage over the vehicle lifetime, which is used to estimate th e impact of proposed fuel economy standards on future fuel consumption and operating co sts. (“Current” refers to the 1995 VMTSurvivability schedule whereas “Updated” deno tes newly acquired information utilized in updating the 1995 schedule.)

1.1. Passenger Cars

The 20-year schedule 1 for passenger car survivability currently in use by the National Highway Traffic Safety Administration ( NHTSA) was developed from R.L. Polk & Company data on registered ve hicles in use by model year over the calendar years 1975 to 1993. The vehicle miles traveled (VMT) sc hedule currently used for passenger cars is
derived from the 1991 Residential Transportation Energy Consumption Survey (RTECS)—which was designed by the Energy In formation Administration (EIA) of the Department of Energy (DOE)—to collect info rmation on the use of energy in residential
vehicles in the United States.

These passenger car schedules are shown in Table 1. The fourth column of Table 1, “Weighted Average Yearly Trav el,” is the product of th e previous two columns—the survivability and VMT schedules. The aver age lifetime passenger car weighted VMT is simply the sum of the yearly average travel miles over the lifetime of the car. In this case, we estimated that a passenger car would last roughly 20 years and travel a lifetime mileage of 126,665 miles.

1.2. Light Trucks

The survivability and VMT 25 year schedules currently used by NHT SA for light truck regulatory impact analyses are shown in Table 2. Survivab ility data was obtained from 1975 to 1993 R.L. Polk and Company registratio ns on trucks in opera tion. Light truck
VMT data was also taken from the 1991 RTECS.

The weighted yearly travel was again the pr oduct of survivability and VMT. The total light truck weighted VMT calculated from these schedules was 153,698 miles.

Note that based on the 1975 to 1993 Polk data, 7.9 percent of passenge r cars are still on the road after 20 years and 12.1 pe rcent of light trucks are stil l on the road after 25 years.

1 Updated Vehicle Survivability and Travel Mileage Schedules , NHTSA (Report Number: DOT HS 808 339), November 1995.3 Table 1 Current Yearly Travel, Survival Probability, and Weighted Yearly Travel as a Function of Passenger Car Vehicle Age

Vehicle Age Estimated Survivability Estimated VMT (exponential model) Weighted Average Yearly Travel Miles 1 0.995 13,533 13,459 2 0.988 12,989 12,839 3 0.978 12,466 12,191 4 0.962 11,964 11,505 5 0.938 11,482 10,776 6 0.908 11,020 10,005 7 0.870 10,577 9,200 8 0.825 10,151 8,376 9 0.775 9,742 7,549 10 0.721 9,350 6,737 11 0.644 8,974 5,779 12 0.541 8,613 4,662 13 0.445 8,266 3,675 14 0.358 7,933 2,843 15 0.285 7,614 2,167 16 0.223 7,308 1,632 17 0.174 7,014 1,218 18 0.134 6,731 902 19 0.103 6,460 665 20 0.079 6,200 488 Lifetime Miles Traveled for Passenger Cars 126,6654 Table 2 Current Yearly Travel, Survival Probability, and Weighted Yearly Travel as a Function of Light Truck Vehicle Age

Vehicle Age Estimated Survivability Estimated VMT (exponential model) Weighted Average Yearly Travel Miles 1 0.998 12,885 12,853 2 0.995 12,469 12,401 3 0.989 12,067 11,937 4 0.980 11,678 11,450 5 0.967 11,302 10,932 6 0.949 10,938 10,376 7 0.924 10,585 9,782 8 0.894 10,244 9,154 9 0.857 9,914 8,498 10 0.816 9,594 7,825 11 0.795 9,285 7,378 12 0.734 8,985 6,593 13 0.669 8,696 5,820 14 0.604 8,415 5,079 15 0.539 8,144 4,387 16 0.476 7,882 3,755 17 0.418 7,628 3,187 18 0.364 7,382 2,686 19 0.315 7,144 2,250 20 0.271 6,913 1,875 21 0.232 6,691 1,555 22 0.198 6,475 1,285 23 0.169 6,266 1,058 24 0.143 6,064 869 25 0.121 5,869 712 Lifetime Miles Traveled for Light Trucks 153,6985 2. Data Sources

The primary source of data for determining ve hicles in operation is the National Vehicle Population Profile (NVPP) compiled by R.L. Polk and Company. The NVPP is an annual census, as of July 1 of each year, of pa ssenger cars and light trucks registered for on-road operation in the United States. NVPP registration data was utilized from vehicle model years 1977 to 2003. Survival rates were averaged for the five most recent model years for vehicles up to 20 years old.

Recent government-sponsored surveys of vehicl e travel attempted to develop up-to-date VMT schedules. One such survey is the 2001 National Household Travel Survey (NHTS)—previously called the Nationwide Personal Tran sportation Survey (NPTS)— sponsored by the Federal Highway Administra tion, Bureau of Transportation Statistics, and the National Highway Traffic Safety Admi nistration. The NHTS is the integration of two national travel surveys: the Federal Highway Administration- sponsored Nationwide Personal Transportation Survey (NPTS) and th e Bureau of Transportation Statisticssponsored American Travel Survey (ATS).

The Residential Transportation Energy Cons umption Survey (RTECS) was designed by the Energy Information Administration (EIA) of the Department of Energy (DOE) to collect information on the use of energy in re sidential vehicles in the United States. Included are data regarding the number and type of vehicles in the residential sector, the characteristics of these vehicles, the per hous ehold and per vehicle VMT, the vehicle fuel consumption and expenditures, and vehicle fu el efficiencies. Th e DOE/EIA RTECS was discontinued after 1994, thus the NHTS was used in its place.6 3. Survivability Analysis

3.1. Passenger Cars

The passenger car survival rate 2 schedule based on 1977 to 2003 NVPP registrations is shown in Table 3. Since the annual NVPP regist ration data is tabulated as of July 1 and model year production ends seve ral months later, the total production for model year N will appear in the NVPP data for calendar year N+1. Therefore, the survivability for vehicles with age A will be found in NVPP calendar year N+1+A, which is A+1 years after model year N. Taking the 1977 model y ear (MY) vehicles as an example, calendar year (CY) 1978 is assumed to have the total production for MY 1977. Thus, CY 1978 would be the base-line year for MY 1977. In addition, CY 1978 would represent a vehicle age of zero years for MY 1977; CY 1979 vehicles would be one year old, and so on. Therefore, the original survival rates we re adjusted upward by one year to reflect the actual survivability computed from the NVPP registration data.

A piece-wise linear relationship appeared to exist between “LN( –LN(1 – Survival Rate))” and “Vehicle Age.” Two linear regr essions were performed for cars up to and including 10 years old and for cars over 10 years old to produce an accurate estimate for
survival rate as a function of vehicl e age. This yielded the following:

Estimated Survival Rate = 1 – EXP[ –EXP(A + B × Age)] (regression model)

where,

for Age ≤ 10 for Age > 10
A = 1.64905 3.38136
B = -0.12143 -0.28623

r 2 = 0.9921 0.9985

The regression estimates produced a 0.9921 coefficient of determination (r 2 ) for vehicle age 10 years old and less, and 0.9985 for vehi cles greater than 10 years old. The

2 Survival rate as used in this report is defined as th e ratio of the number of vehi cles remaining in the fleet at a given year as compared to a base-line year. Co ntinuing with the example from above, as mentioned before, the number of MY 1977 vehicles sold in CY 1978 would serve as the base-line year for MY 1977 vehicles. In other words, CY 1978 would represent year zero (a base-line year) for MY 1977 vehicles, and the survival rate of MY 1977 vehicles in CY 1978 would be 1.0 (the number of MY 1977 vehicles in the fleet divided by to the number of MY 1977 vehicles sold is equal to one). In the following year, CY 1979, MY 1977 vehicles would be one year old. We would expect that the number of MY 1977 vehicles to have
diminished due to reasons such as acci dents, thefts, etc. and thus the surv ival rate would be less then 1.0; for CY 1980, the survival rate would be less then that found in CY 1979, and so on.

A table of the survival rates as a function of the vehicl e’s age (rather than as a function of its model year or the calendar year) was generated so that vehicles of di ffering model years, but th e same vehicle age, could be matched-up to arrive at a five-year average survival rate for a particul ar vehicle age (e.g ., three year-old vehicles are averaged together but maybe comprised of vehicles from model years 1995, 1996, 1997, 1998, and 1999).7 estimated survival rates were computed for ve hicle ages 1 to 25 year s old using the above regression model and appropriate re gression coefficients, A and B.

The current passenger car estimated survivab ility schedule (1975 to 1993 NVPP data) is presented with the updated estimated survivab ility (1977 to 2002 NVPP data) in Figure 1. The current survivability is nearly equal to the updated survivability for newer cars up to five years old. For middle-aged to older cars between 6 and 20 years old, the updated survivability schedule indicates that newer cars are lasting longer as compared to the previous survivability schedule.8 Table 3 Survivability of Passenger Cars by Vehicle Age

from 1977 to 2002 NVPP Registration Data

Vehicle Age Adjusted
Survival Rate LN(1-SR) LN(-LN(1-SR)) Estimated
Survival Rate
1 0.9913 -4.7480 1.5577 0.9900
2 0.9809 -3.9571 1.3755 0.9831
3 0.9694 -3.4875 1.2492 0.9731
4 0.9555 -3.1130 1.1356 0.9593
5 0.9423 -2.8525 1.0482 0.9413
6 0.9227 -2.5603 0.9401 0.9188
7 0.9008 -2.3105 0.8374 0.8918
8 0.8703 -2.0426 0.7142 0.8604
9 0.8288 -1.7647 0.5680 0.8252
10 0.7703 -1.4708 0.3858 0.7866
11 0.6958 -1.1902 0.1741 0.7170
12 0.6107 -0.9435 -0.0581 0.6125
13 0.5187 -0.7312 -0.3130 0.5094
14 0.4244 -0.5524 -0.5935 0.4142
15 0.3425 -0.4193 -0.8691 0.3308
16 0.2653 -0.3083 -1.1766 0.2604
17 0.2000 -0.2231 -1.5000 0.2028
18 0.1500 -0.1626 -1.8167 0.1565
19 0.1185 -0.1262 -2.0703 0.1200
20 0.0928 -0.0974 -2.3288 0.0916
21 0.0696
22 0.0527
23 0.0399
24 0.0301
25 0.02279Figure 1Passenger Car Survivabilityby Vehicle Age0.0000.1000.2000.3000.4000.5000.6000.7000.8000.9001.0000 5 10 15 20 25Vehicle Age

Survivability1975-1993 NVPP (estimate)1977-2002 NVPP (estimate)1977-2002 NVPP (actual)10 3.2 Light Trucks

The light truck survivability computed from NV PP registrations is presented in Table 4. As was done with passenger cars, two linear regressions of “LN(–LN(1–Actual Survival Rate))” with the vehicle age adjusted were produced for light trucks up to and including 12 years of age and for light trucks greater th an 12 years old. The cut-off point between the two linear regressions was increased by tw o years, relative to the previous study, for light trucks to produce a bette r fit and “smoother” curve.

Estimated Survival Rate = 1 – EXP[ –EXP(A + B × Age)] (regression model)

for Age ≤ 12 for Age > 12
A = 1.42048 1.64815
B = -0.12470 -0.14373

r 2 = 0.97774 0.99662

A comparison of the current light truck surviv ability schedule with the updated survival rate schedule is presented in Figure 2. Unlik e passenger cars, it is readily apparent that, based on the updated survivability schedule, you nger light trucks are not lasting as long as younger light trucks from the current schedu le. The most likely explanation is that there is an increase in usage of light truc ks as passenger vehicles, thus raising the exposure of light trucks to crashes and rollo vers. This trend lasts approximately until 20 years of age, achieving a maximum differe nce of about 0.1445 at 11 years of age. Beyond 20 years of age, the survivability rate s of both schedules begin to converge.

It is interesting to compare the updated pa ssenger car survival ra tes with updated light truck survival rates. A highe r percentage of pass enger cars are surviving longer early in their lives relative to light trucks of comparable vint age (up to about age 12). (Conversely, the 1995 VMT-survivability schedu le illustrates the opposite trend, namely, light trucks are surviving l onger early in their lives when compared to passenger cars.)11 Table 4 Survivability of Light Trucks by Vehicle Age

from 1977 to 2002 NVPP Registration Data

Vehicle Age Adjusted
Survival Rate LN(1-SR) LN(-LN(1-SR)) Estimated
Survival Rate
1 0.9854 -4.2247 1.4409 0.9741
2 0.9598 -3.2141 1.1675 0.9603
3 0.9318 -2.6857 0.9879 0.9420
4 0.9043 -2.3466 0.8530 0.9190
5 0.8704 -2.0431 0.7145 0.8913
6 0.8387 -1.8247 0.6014 0.8590
7 0.8114 -1.6683 0.5118 0.8226
8 0.7858 -1.5408 0.4323 0.7827
9 0.7533 -1.3998 0.3363 0.7401
10 0.7149 -1.2549 0.2270 0.6956
11 0.6651 -1.0938 0.0896 0.6501
12 0.6163 -0.9580 -0.0429 0.6040
13 0.5605 -0.8221 -0.1959 0.5517
14 0.5037 -0.7005 -0.3560 0.5009
15 0.4460 -0.5905 -0.5268 0.4522
16 0.4005 -0.5117 -0.6699 0.4062
17 0.3597 -0.4458 -0.8078 0.3633
18 0.3186 -0.3836 -0.9580 0.3236
19 0.2884 -0.3403 -1.0781 0.2873
20 0.2613 -0.3029 -1.1945 0.2542
21 0.2244
22 0.1975
23 0.1735
24 0.1522
25 0.1332
26 0.1165
27 0.1017
28 0.0887
29 0.0773
30 0.0673
31 0.0586
32 0.0509
33 0.0443
34 0.0385
35 0.0334
36 0.029012Figure 2Light Truck Survivabilityby Vehicle Age0.0000.1000.2000.3000.4000.5000.6000.7000.8000.9001.0000 5 10 15 20 25 30 35 40Vehicle Age (years)

Survivability1975-1993 NVPP (estimate)1977-2002 NVPP (estimate)1977-2002 NVPP (actual)13 4. VMT Analysis

The annual vehicle miles traveled (VMT) as a function of vehicle age for passenger cars up to 25 years old and light trucks up to 30 years old with thei r respective weighting
factor 3 from the 2001 NHTS is shown in Table 5 and Table 6, respectively. Prior to the 1995 NPTS, FHWA collected VMT data by aski ng consumers to estimate the number of miles they drive in a given year. Star ting with the 1995 NPTS, FHWA changed their methodology and collected two odometer read ings over a two-month period and then
annualized the difference to arrive at an a nnual VMT. The data was collected over a 14- month period, starting in March 2001 and ending in Ma y 2002. Since model year 2002 vehicles begin to appear in September 2001, and were already about eight months old by the end of the survey, it was assumed that 2002 vehicles were one year old in the VMT analysis, MY 2001 vehicles ar e two years old, and so on.

A brief overview of the methodology of how the fi nal data set that was used is discussed herein. Focusing on the variable "VEHTYPE", for the passenger car VMT analysis, all records pertaining to automob ile vehicle types were include d whereas those relating to any other vehicle types were eliminated. Conversely, for th e light truck VMT analysis, records dealing with passenger cars were el iminated. Also, all records pertaining to "Other", "Motorcycle", "Refused", and "Don't Know" were also removed.

Next, we looked at the variab le "VEHYEAR." Since we co uld not calculate a vehicle without its model year, we eliminated all r ecords pertaining to "Ref used", "Don't Know", and "Not Ascertained"; in other words, t hose that did not respond were not included.

Lastly, we then turned to the variable "BESTMILE." All records pertaining to "Appropriate Skip", "Refused", "Don't Know", and "Not Ascertained" were eliminated. Doing this deleted all records for which “VEH TYPE” is "RV" or "Other Truck" (i.e., all
BESTMILES were blank for thos e types at this point).

In addition, when the variable “BESTMILE” 4 was equal to zero, the record was flagged and the mileage was confirmed with another mileage variable, “ANNMILE.” If “ANNMILE” was not zero, then the value of ANNMILE was taken to be the annual mileage. However, if “ANNMILE” was also zero, then it was assumed that the vehicle did, indeed, travel zero miles in a given year and the record was not included in the study.

3 The weighting factors were derived based on various factors such the time of year sampled, geographic location, household size, and so on. More information can be found in Chapter 5 and Chapter 7, Section D of the 2001 NHTS User’s Guide, which can be found at http://nhts.ornl.gov/2001/usersguide/index.shtml.

4 The variable “BESTMILE” is an attempt to choose th e best estimate of the annual mileage for a vehicle. This best guess is derived from two sources: an annualized mileage based on two odometer readings that are approximately two months apart (recorded in the variable “ANNUALI ZED”); the other figure is based on a driver’s reported estimate of how many miles were driven in a given year (variable “ANNMILES”).14 4.1. Passenger Cars

After inspection of the data, a linear rela tionship between VMT and vehicle age was postulated. In addition, wh ereas the current schedul e assumed an exponential relationship between VMT and vehicle age, a cubic relationship between age and mileage was postulated and found to have a very good fit. Utilizing the statistical software package, STATATM v8.2, a weighted regression analysis was performed, and resulted in the following:

Estimated VMT = A × (Age) 3 + B × (Age) 2 + C × (Age) + D
A B C D r 2 Cubic Polynomial
Model 0.3672131 -13.21949 -232.8491 14476.36 0.9689

A comparison of the current and updated VMT schedules as well as the actual VMT data from the 2001 NHTS survey as a function of vehicle age is presented in Table 5 and Figure 3 for passenger vehicles.

Each record has an associated weighting f actor accompanying it so that users of the NHTS data are able to, if need be, bring up the individual records to a representative level. The column “Sum of Weights” is th e arithmetic sum of all the weighting factors for a particular age of a vehicle.15 Table 5 VMT Schedule for Passenger Cars from 2001 FHWA NHTS

Vehicle Age (years) Actual VMT (miles) Sum of Weights Estimated VMT
Cubic Model

1 14,417 5,813,974 14,231 2 13,803 8,439,630 13,961 3 13,692 7,801,493 13,669 4 13,415 7,636,047 13,357 5 13,183 7,816,479 13,028 6 12,301 6,835,019 12,683 7 12,253 7,999,905 12,325 8 11,709 7,009,223 11,956 9 11,893 6,529,853 11,578 10 11,855 6,021,879 11,193 11 10,620 5,913,173 10,804 12 9,986 5,046,971 10,413 13 10,248 5,213,460 10,022 14 9,515 3,615,932 9,633 15 9,168 3,262,131 9,249 16 8,636 2,659,611 8,871 17 8,941 2,120,955 8,502 18 7,267 1,597,538 8,144 19 8,890 919,359 7,799 20 8,759 536,793 7,469 21 6,878 477,866 7,157 22 7,242 498,306 6,866 23 6,350 545,822 6,596 24 5,745 441,636 6,350 25 4,130 313,988 6,13116Figure 3Estimated Passenger Car VMTby Vehicle Age02,0004,0006,0008,00010,00012,00014,00016,0000 5 10 15 20 25Vehicle Age (years)

VMT (miles)Estimated VMT (1991 DOE/EIA RTECS)Estimated VMT (2001 NHTS)Actual VMT (2001 NHTS)17 4.2. Light Trucks

Similar to passenger cars, a cubic model wa s hypothesized and a linear regression was performed based on the model.

Estimated VMT = A × (Age) 3 + B × (Age) 2 + C × (Age) + D
A B C D r 2 Cubic Polynomial
Model 0.6806403 -22.844801 -238.5518 16345.32 0.9634

Unlike the passenger car where the linear regr ession curve declines as the vehicles age increases up to its lifespan of 25 years, fo r light trucks, we reach an inflection point 5 within the lifespan of the tr uck at an approximate vehicle age of 27 years. In other words, after year 27, the VMT begins to in crease rather than steadily decrease. To remedy this problem, we take the lowest esti mated VMT that the truck will travel and use that as the annual mileage for the remaini ng lifespan of the truck. Thus, the lowest mileage that we estimate the truck will travel occurs in year 27 with a value of 6,648 miles, and is the value we use up to remai nder of the lifetime of the truck (36 years).

Age ≤ 27
Estimated VMT = A × (Age) 3 + B × (Age) 2 + C × (Age) + D
A B C D r 2

0.6806403 -22.84481 -238.5518 16345.32 0.9634

27 < Age ≤ 36 Cubic Polynomial
Model

Estimated VMT = 6,648

The results are presented below in Table 6, and a comparison of the current and updated
VMT as well as the actual VMT are available in Figure 4. In Table 6, The “Unadjusted”
sub-column under the main column “Estimated VMT Cubic Model” lis ts the values of the annual mileage based on the cubic regres sion model from above. As mentioned before and evidenced in the table, at y ear 27 the VMT reaches a minimum and then begins to increase after that; the “Adjusted” sub-column corrects this by taking the lowest VMT reached (6,648 miles) and uses that value for the remainder of the lifetime of the light truck.

Judging from Figure 4 and comparing the “Act ual VMT” with the estimated “Adjusted” VMT after year 27, this assumption seems to tr ack well with the real-world data. To be certain, we performed a weight ed average of the “Actual VMT” data from a vehicle age of 27 to 32, and arrive at a value of about 7,172 miles, which is not too far from our assumption of 6,648 miles. In addition, the VMT weighted by the survivability rate is of more relevance than the “unweighted” VMT, a nd since the survivability rates are fairly low after year 27, those weighted miles be yond year 27 contribute ve ry little to the
lifetime miles traveled. In f act, because the mileage is take n to be a constant 6,648 miles

5 An inflection point is a point on a curve at which the sign of the curvature (i.e., the concavity) changes. In our case, the concavity changes from down (or negative) to up (or positive) at an approximate vehicle age of 27 years.18 over time rather than decreasing, the wei ghted VMT (by survivability rate) and the lifetime VMT for light trucks are potentially over-estimated.19 Table 6 VMT Schedule for Light Tr ucks from 2001 FHWA NHTS

Estimated VMT Cubic Model Vehicle Age Actual VMT Sum of Weights Unadjusted Adjusted
1 15,806 5,612,464 16,085 16,085 2 15,683 7,432,237 15,782 15,782 3 15,859 6,745,541 15,442 15,442 4 15,302 6,062,588 15,069 15,069 5 14,762 5,315,874 14,667 14,667 6 13,836 4,720,786 14,239 14,239 7 13,542 4,611,752 13,790 13,790 8 13,615 4,519,253 13,323 13,323 9 12,875 3,623,754 12,844 12,844 10 12,203 3,167,817 12,356 12,356 11 11,501 2,723,295 11,863 11,863 12 10,815 2,694,645 11,369 11,369 13 11,391 2,596,898 10,879 10,879 14 10,843 2,228,663 10,396 10,396 15 10,378 1,849,371 9,924 9,924 16 9,259 1,907,149 9,468 9,468 17 8,358 1,495,622 9,032 9,032 18 9,371 1,149,093 8,619 8,619 19 7,352 738,596 8,234 8,234 20 8,363 448,094 7,881 7,881 21 6,999 353,464 7,565 7,565 22 7,327 329,249 7,288 7,288 23 6,969 609,914 7,055 7,055 24 6,220 500,876 6,871 6,871 25 6,312 357,861 6,739 6,739 26 6,745 272,612 6,663 6,663 27 9,515 224,307 6,648 6,648 28 6,635 152,987 6,697 6,648 29 12,108 196,936 6,815 6,648 30 5,067 278,648 7,006 6,648 31 4,577 144,194 7,273 6,648 32 6,923 124,329 7,622 6,648
33 8,055 6,648
34 8,578 6,648
35 9,194 6,648
36 9,907 6,64820Figure 4Estimated Light Truck VMTby Vehicle Age02,0004,0006,0008,00010,00012,00014,00016,00018,0000 5 10 15 20 25 30 35 40Vehicle Age (years)

VMT (miles)Estimated VMT (1991 DOE/EIA RTECS)Estimated VMT (2001 NHTS)Actual VMT (2001 NHTS)21 5. Lifetime Mileage

5.1. Passenger Cars

The annual estimated weighted VMT and e xpected lifetime passenger car VMT (based on the updated 1977 to 2002 NVPP and 2001 NHTS data) is shown in Table 7. The “expected passenger car lifetime VMT” is calculated by summing the “estimated weighted VMT” over the number of years the ve hicle is expected to be in service (25 years in the case of passenge r cars), where the weighted VMT is simply the product of the “estimated survivability” and the “estimated VMT.”

Figure 5 compares the current weighted VM T schedule with the updated weighted VMT
schedule.22 Table 7 Summary of Updated Results and Es timated Lifetime Passenger Car VMT
Estimated Survivability Estimated VMT Vehicle Age

(1977 to 2002 NVPP) (2001 NHTS) Weighted Yearly
Travel Miles

1 0.9900 14,231 14,089 2 0.9831 13,961 13,725 3 0.9731 13,669 13,300 4 0.9593 13,357 12,813 5 0.9413 13,028 12,262 6 0.9188 12,683 11,652 7 0.8918 12,325 10,991 8 0.8604 11,956 10,287 9 0.8252 11,578 9,554 10 0.7866 11,193 8,804 11 0.7170 10,804 7,746 12 0.6125 10,413 6,378 13 0.5094 10,022 5,105 14 0.4142 9,633 3,990 15 0.3308 9,249 3,060 16 0.2604 8,871 2,310 17 0.2028 8,502 1,724 18 0.1565 8,144 1,275 19 0.1200 7,799 936 20 0.0916 7,469 684 21 0.0696 7,157 498 22 0.0527 6,866 362 23 0.0399 6,596 263 24 0.0301 6,350 191 25 0.0227 6,131 139

Estimated Passenger Car Lifetime VMT 152,13723Figure 5Passenger Car Weighted VMTby Vehicle Age02,0004,0006,0008,00010,00012,00014,00016,0000 5 10 15 20 25Vehicle Age (years)

Weighted VMT (miles)Current Weighted VMTUpdated Weighted VMT24 5.2. Light Trucks

The annual estimated weighted VMT and e xpected lifetime passenger car VMT (based on the updated 1977 to 2002 NVPP and 2001 NHTS data) is shown in Table 8. The “expected light truck lifetime VMT” is calc ulated by summing the “estimated weighted VMT” over the number of years the vehicle is ex pected to be in service (36 years in the case of light trucks), where the weighted VMT is simply the product of the “estimated survivability” and the “estimated VMT.”

Figure 6 compares the current weighted VM T schedule with the updated weighted VMT
schedule.25 Table 8 Summary of Updated Results and Es timated Lifetime Light Truck VMT
Estimated Survivability Estimated VMT Vehicle Age

(1977 to 2002 NVPP) (2001 NHTS) Weighted Yearly
Travel Miles

1 0.9741 16,085 15,668 2 0.9603 15,782 15,155 3 0.9420 15,442 14,547 4 0.9190 15,069 13,849 5 0.8913 14,667 13,072 6 0.8590 14,239 12,230 7 0.8226 13,790 11,343 8 0.7827 13,323 10,428 9 0.7401 12,844 9,506 10 0.6956 12,356 8,595 11 0.6501 11,863 7,712 12 0.6040 11,369 6,867 13 0.5517 10,879 6,002 14 0.5009 10,396 5,207 15 0.4522 9,924 4,488 16 0.4062 9,468 3,846 17 0.3633 9,032 3,281 18 0.3236 8,619 2,790 19 0.2873 8,234 2,366 20 0.2542 7,881 2,004 21 0.2244 7,565 1,697 22 0.1975 7,288 1,440 23 0.1735 7,055 1,224 24 0.1522 6,871 1,046 25 0.1332 6,739 898 26 0.1165 6,663 776 27 0.1017 6,648 676 28 0.0887 6,648 590 29 0.0773 6,648 514 30 0.0673 6,648 448 31 0.0586 6,648 389 32 0.0509 6,648 339 33 0.0443 6,648 294 34 0.0385 6,648 256 35 0.0334 6,648 222 36 0.0290 6,648 193

Estimated Lifetime Light Truck VMT 179,95426Figure 6Light Truck Weighted VMTby Vehicle Age02,0004,0006,0008,00010,00012,00014,00016,0000 5 10 15 20 25 30 35 40Vehicle Age (years)

Weighted VMT (miles)Current Weighted VMTUpdated Weighted VMT27 6. Discount Factors

Frequently, the agency discounts future safety benefits or fuel economy impacts back to present value to compare them to costs that incur when the vehicle is purchased. The present discount factors used are based on half-year discount rate s with the following
formula:

Present Discount Factor =

2 1 ) 1 ( 1

−

+ N

i Equation 1

where, N = vehicle age (years)

i = discount rate (e.g., 3 per cent, 7 percent, 10 percent).

Each present discount (PD) factor for a give n vehicle age and discount rate is multiplied by their respective “Percent To tal VMT” to arrive at the “Weighted Present Discount (PD) Factors” in the last columns of Ta bles 9 and 10. For example in Table 9a, passenger cars with a vehicle ag e of 10 years and a discount rate of 3 percent results in a weighted present discount f actor of 0.0437 (results from mu ltiplying the percent total VMT of 5.79 percent by the presen t discount value factor of 0.7552).

Summing the entire range of “Annual Weighted Present Discount Factor” for a particular vehicle and discount rate gi ves us the “Lifetime Weight ed Present Value Discount Factor” for that particular ve hicle type and at that disc ount rate; for passenger cars, 0.8304 (at 3 percent), 0.6700 (7 percent), and 0.5824 (10 percent); for light trucks, 0.8022 (at 3 percent), 0.6303 (7 per cent), and 0.5419 (10 percent).28 Table 9a Updated Passenger Car Weighted Present Value Discount Factor (at 3 Percent)

Vehicle

Age (years) VMT Survival Probability Weighted
VMT Percent of
Total VMT Present Discount
Factors Annual Weighted PD

Factors at 3% 1 14,231 0.9900 14,089 9.26% 0.9853 0.0912 2 13,961 0.9831 13,725 9.02% 0.9566 0.0863 3 13,669 0.9731 13,300 8.74% 0.9288 0.0812 4 13,357 0.9593 12,813 8.42% 0.9017 0.0759 5 13,028 0.9413 12,262 8.06% 0.8755 0.0706 6 12,683 0.9188 11,652 7.66% 0.8500 0.0651 7 12,325 0.8918 10,991 7.22% 0.8252 0.0596 8 11,956 0.8604 10,287 6.76% 0.8012 0.0542 9 11,578 0.8252 9,554 6.28% 0.7778 0.0488 10 11,193 0.7866 8,804 5.79% 0.7552 0.0437 11 10,804 0.7170 7,746 5.09% 0.7332 0.0373 12 10,413 0.6125 6,378 4.19% 0.7118 0.0298 13 10,022 0.5094 5,105 3.36% 0.6911 0.0232 14 9,633 0.4142 3,990 2.62% 0.6710 0.0176 15 9,249 0.3308 3,060 2.01% 0.6514 0.0131 16 8,871 0.2604 2,310 1.52% 0.6324 0.0096 17 8,502 0.2028 1,724 1.13% 0.6140 0.0070 18 8,144 0.1565 1,275 0.84% 0.5961 0.0050 19 7,799 0.1200 936 0.62% 0.5788 0.0036 20 7,469 0.0916 684 0.45% 0.5619 0.0025 21 7,157 0.0696 498 0.33% 0.5456 0.0018 22 6,866 0.0527 362 0.24% 0.5297 0.0013 23 6,596 0.0399 263 0.17% 0.5142 0.0009 24 6,350 0.0301 191 0.13% 0.4993 0.0006 25 6,131 0.0227 139 0.09% 0.4847 0.0004 Lifetime Weighted Present Value Discount Factor 0.830429 Table 9b Updated Passenger Car Weighted Present Value Discount Factor (at 7 Percent)

Vehicle

Age (years) VMT Survival Probability Weighted
VMT Percent of
Total VMT Present Discount
Factors Annual Weighted PD

Factors at
7% 1 14,231 0.9900 14,089 9.26% 0.9667 0.0895 2 13,961 0.9831 13,725 9.02% 0.9035 0.0815 3 13,669 0.9731 13,300 8.74% 0.8444 0.0738 4 13,357 0.9593 12,813 8.42% 0.7891 0.0665 5 13,028 0.9413 12,262 8.06% 0.7375 0.0594 6 12,683 0.9188 11,652 7.66% 0.6893 0.0528 7 12,325 0.8918 10,991 7.22% 0.6442 0.0465 8 11,956 0.8604 10,287 6.76% 0.6020 0.0407 9 11,578 0.8252 9,554 6.28% 0.5626 0.0353 10 11,193 0.7866 8,804 5.79% 0.5258 0.0304 11 10,804 0.7170 7,746 5.09% 0.4914 0.0250 12 10,413 0.6125 6,378 4.19% 0.4593 0.0193 13 10,022 0.5094 5,105 3.36% 0.4292 0.0144 14 9,633 0.4142 3,990 2.62% 0.4012 0.0105 15 9,249 0.3308 3,060 2.01% 0.3749 0.0075 16 8,871 0.2604 2,310 1.52% 0.3504 0.0053 17 8,502 0.2028 1,724 1.13% 0.3275 0.0037 18 8,144 0.1565 1,275 0.84% 0.3060 0.0026 19 7,799 0.1200 936 0.62% 0.2860 0.0018 20 7,469 0.0916 684 0.45% 0.2673 0.0012 21 7,157 0.0696 498 0.33% 0.2498 0.0008 22 6,866 0.0527 362 0.24% 0.2335 0.0006 23 6,596 0.0399 263 0.17% 0.2182 0.0004 24 6,350 0.0301 191 0.13% 0.2039 0.0003 25 6,131 0.0227 139 0.09% 0.1906 0.0002 Lifetime Weighted Present Value Discount Factor 0.670030 Table 9c Updated Passenger Car Weighted Present Value Discount Factor (at 10 Percent)

Vehicle

Age (years) VMT Survival Probability Weighted
VMT Percent of
Total VMT Present Discount
Factors Annual Weighted PD

Factors at 10% 1 14,231 0.9900 14,089 9.26% 0.9535 0.0883 2 13,961 0.9831 13,725 9.02% 0.8668 0.0782 3 13,669 0.9731 13,300 8.74% 0.7880 0.0689 4 13,357 0.9593 12,813 8.42% 0.7164 0.0603 5 13,028 0.9413 12,262 8.06% 0.6512 0.0525 6 12,683 0.9188 11,652 7.66% 0.5920 0.0453 7 12,325 0.8918 10,991 7.22% 0.5382 0.0389 8 11,956 0.8604 10,287 6.76% 0.4893 0.0331 9 11,578 0.8252 9,554 6.28% 0.4448 0.0279 10 11,193 0.7866 8,804 5.79% 0.4044 0.0234 11 10,804 0.7170 7,746 5.09% 0.3676 0.0187 12 10,413 0.6125 6,378 4.19% 0.3342 0.0140 13 10,022 0.5094 5,105 3.36% 0.3038 0.0102 14 9,633 0.4142 3,990 2.62% 0.2762 0.0072 15 9,249 0.3308 3,060 2.01% 0.2511 0.0050 16 8,871 0.2604 2,310 1.52% 0.2283 0.0035 17 8,502 0.2028 1,724 1.13% 0.2075 0.0024 18 8,144 0.1565 1,275 0.84% 0.1886 0.0016 19 7,799 0.1200 936 0.62% 0.1715 0.0011 20 7,469 0.0916 684 0.45% 0.1559 0.0007 21 7,157 0.0696 498 0.33% 0.1417 0.0005 22 6,866 0.0527 362 0.24% 0.1288 0.0003 23 6,596 0.0399 263 0.17% 0.1171 0.0002 24 6,350 0.0301 191 0.13% 0.1065 0.0001 25 6,131 0.0227 139 0.09% 0.0968 0.0001 Lifetime Weighted Present Value Discount Factor 0.582431 Table 10a Updated Light Truck Weighted Present Value Discount Factor (at 3 Percent)

Vehicle

Age (years) VMT Survival Probability Weighted
VMT Percent of
Total VMT Present Discount
Factors Annual Weighted PD

Factors at 3% 1 16,085 0.9741 15,668 8.71% 0.9853 0.0858 2 15,782 0.9603 15,155 8.42% 0.9566 0.0806 3 15,442 0.9420 14,547 8.08% 0.9288 0.0751 4 15,069 0.9190 13,849 7.70% 0.9017 0.0694 5 14,667 0.8913 13,072 7.26% 0.8755 0.0636 6 14,239 0.8590 12,230 6.80% 0.8500 0.0578 7 13,790 0.8226 11,343 6.30% 0.8252 0.0520 8 13,323 0.7827 10,428 5.79% 0.8012 0.0464 9 12,844 0.7401 9,506 5.28% 0.7778 0.0411 10 12,356 0.6956 8,595 4.78% 0.7552 0.0361 11 11,863 0.6501 7,712 4.29% 0.7332 0.0314 12 11,369 0.6040 6,867 3.82% 0.7118 0.0272 13 10,879 0.5517 6,002 3.34% 0.6911 0.0230 14 10,396 0.5009 5,207 2.89% 0.6710 0.0194 15 9,924 0.4522 4,488 2.49% 0.6514 0.0162 16 9,468 0.4062 3,846 2.14% 0.6324 0.0135 17 9,032 0.3633 3,281 1.82% 0.6140 0.0112 18 8,619 0.3236 2,790 1.55% 0.5961 0.0092 19 8,234 0.2873 2,366 1.31% 0.5788 0.0076 20 7,881 0.2542 2,004 1.11% 0.5619 0.0063 21 7,565 0.2244 1,697 0.94% 0.5456 0.0051 22 7,288 0.1975 1,440 0.80% 0.5297 0.0042 23 7,055 0.1735 1,224 0.68% 0.5142 0.0035 24 6,871 0.1522 1,046 0.58% 0.4993 0.0029 25 6,739 0.1332 898 0.50% 0.4847 0.0024 26 6,663 0.1165 776 0.43% 0.4706 0.0020 27 6,648 0.1017 676 0.38% 0.4569 0.0017 28 6,648 0.0887 590 0.33% 0.4436 0.0015 29 6,648 0.0773 514 0.29% 0.4307 0.0012 30 6,648 0.0673 448 0.25% 0.4181 0.0010 31 6,648 0.0586 389 0.22% 0.4059 0.0009 32 6,648 0.0509 339 0.19% 0.3941 0.0007 33 6,648 0.0443 294 0.16% 0.3826 0.0006 34 6,648 0.0385 256 0.14% 0.3715 0.0005 35 6,648 0.0334 222 0.12% 0.3607 0.0004 36 6,648 0.0290 193 0.11% 0.3502 0.0004 Lifetime Weighted Present Value Discount Factor 0.802232 Table 10b Updated Light Truck Weighted Present Value Discount Factor (at 7 Percent)

Vehicle

Age (years) VMT Survival Probability Weighted
VMT Percent of
Total VMT Present Discount
Factors Annual Weighted PD

Factors at
7% 1 16,085 0.9741 15,668 8.71% 0.9667 0.0842 2 15,782 0.9603 15,155 8.42% 0.9035 0.0761 3 15,442 0.9420 14,547 8.08% 0.8444 0.0683 4 15,069 0.9190 13,849 7.70% 0.7891 0.0607 5 14,667 0.8913 13,072 7.26% 0.7375 0.0536 6 14,239 0.8590 12,230 6.80% 0.6893 0.0468 7 13,790 0.8226 11,343 6.30% 0.6442 0.0406 8 13,323 0.7827 10,428 5.79% 0.6020 0.0349 9 12,844 0.7401 9,506 5.28% 0.5626 0.0297 10 12,356 0.6956 8,595 4.78% 0.5258 0.0251 11 11,863 0.6501 7,712 4.29% 0.4914 0.0211 12 11,369 0.6040 6,867 3.82% 0.4593 0.0175 13 10,879 0.5517 6,002 3.34% 0.4292 0.0143 14 10,396 0.5009 5,207 2.89% 0.4012 0.0116 15 9,924 0.4522 4,488 2.49% 0.3749 0.0093 16 9,468 0.4062 3,846 2.14% 0.3504 0.0075 17 9,032 0.3633 3,281 1.82% 0.3275 0.0060 18 8,619 0.3236 2,790 1.55% 0.3060 0.0047 19 8,234 0.2873 2,366 1.31% 0.2860 0.0038 20 7,881 0.2542 2,004 1.11% 0.2673 0.0030 21 7,565 0.2244 1,697 0.94% 0.2498 0.0024 22 7,288 0.1975 1,440 0.80% 0.2335 0.0019 23 7,055 0.1735 1,224 0.68% 0.2182 0.0015 24 6,871 0.1522 1,046 0.58% 0.2039 0.0012 25 6,739 0.1332 898 0.50% 0.1906 0.0010 26 6,663 0.1165 776 0.43% 0.1781 0.0008 27 6,648 0.1017 676 0.38% 0.1665 0.0006 28 6,648 0.0887 590 0.33% 0.1556 0.0005 29 6,648 0.0773 514 0.29% 0.1454 0.0004 30 6,648 0.0673 448 0.25% 0.1359 0.0003 31 6,648 0.0586 389 0.22% 0.1270 0.0003 32 6,648 0.0509 339 0.19% 0.1187 0.0002 33 6,648 0.0443 294 0.16% 0.1109 0.0002 34 6,648 0.0385 256 0.14% 0.1037 0.0001 35 6,648 0.0334 222 0.12% 0.0969 0.0001 36 6,648 0.0290 193 0.11% 0.0905 0.0001 Lifetime Weighted Present Value Discount Factor 0.630333 Table 10c Updated Light Truck Weighted Present Value Discount Factor (at 10 Percent)

Vehicle

Age (years) VMT Survival Probability Weighted
VMT Percent of
Total VMT Present Discount
Factors Annual Weighted PD

Factors at 10% 1 16,085 0.9741 15,668 8.71% 0.9535 0.0830 2 15,782 0.9603 15,155 8.42% 0.8668 0.0730 3 15,442 0.9420 14,547 8.08% 0.7880 0.0637 4 15,069 0.9190 13,849 7.70% 0.7164 0.0551 5 14,667 0.8913 13,072 7.26% 0.6512 0.0473 6 14,239 0.8590 12,230 6.80% 0.5920 0.0402 7 13,790 0.8226 11,343 6.30% 0.5382 0.0339 8 13,323 0.7827 10,428 5.79% 0.4893 0.0284 9 12,844 0.7401 9,506 5.28% 0.4448 0.0235 10 12,356 0.6956 8,595 4.78% 0.4044 0.0193 11 11,863 0.6501 7,712 4.29% 0.3676 0.0158 12 11,369 0.6040 6,867 3.82% 0.3342 0.0128 13 10,879 0.5517 6,002 3.34% 0.3038 0.0101 14 10,396 0.5009 5,207 2.89% 0.2762 0.0080 15 9,924 0.4522 4,488 2.49% 0.2511 0.0063 16 9,468 0.4062 3,846 2.14% 0.2283 0.0049 17 9,032 0.3633 3,281 1.82% 0.2075 0.0038 18 8,619 0.3236 2,790 1.55% 0.1886 0.0029 19 8,234 0.2873 2,366 1.31% 0.1715 0.0023 20 7,881 0.2542 2,004 1.11% 0.1559 0.0017 21 7,565 0.2244 1,697 0.94% 0.1417 0.0013 22 7,288 0.1975 1,440 0.80% 0.1288 0.0010 23 7,055 0.1735 1,224 0.68% 0.1171 0.0008 24 6,871 0.1522 1,046 0.58% 0.1065 0.0006 25 6,739 0.1332 898 0.50% 0.0968 0.0005 26 6,663 0.1165 776 0.43% 0.0880 0.0004 27 6,648 0.1017 676 0.38% 0.0800 0.0003 28 6,648 0.0887 590 0.33% 0.0727 0.0002 29 6,648 0.0773 514 0.29% 0.0661 0.0002 30 6,648 0.0673 448 0.25% 0.0601 0.0001 31 6,648 0.0586 389 0.22% 0.0546 0.0001 32 6,648 0.0509 339 0.19% 0.0497 0.0001 33 6,648 0.0443 294 0.16% 0.0452 0.0001 34 6,648 0.0385 256 0.14% 0.0411 0.0001 35 6,648 0.0334 222 0.12% 0.0373 0.0000 36 6,648 0.0290 193 0.11% 0.0339 0.0000 Lifetime Weighted Present Value Discount Factor 0.541934 7. Appendix35 7.1. Corporate Average Fuel Economy (CAFE) VMT Schedules

For a great majority of rulemakings, vehicles ar e classified as either a passenger car or as a light truck with the vehicle miles traveled schedules created to reflect this fact. However, an exception to this practice are the Corporate Average Fuel Economy (CAFE) standards, in which the light truck categorie s are further discriminated into three subcategories based upon the light truck’s body type . These sub-categories are as follows, with the specific vehicle types follo wing in a parenthe tical expression:

• Pickups (open-bed trucks of all sizes);

• SUVs (sport wagons and utility vehicles of all sizes) and

• Vans (minivans, standard and larg e passenger vans, and cargo vans).

Passenger cars remain grouped in their own ca tegory and are not furt her divided, but are listed here for the sake of completeness:

• Passenger cars (coupes, sedans, station wagons, sports cars, and convertibles).

A least-squares fit of the vehi cle miles traveled for each sub-category of light trucks by vehicle age is presented below in Table 11 alongside an aggregated VMT 6 for all light trucks. Since a separate regression was performed on separate sub-categories, the “shape” of the curves will not match that of th e aggregated light truck curve, especially atthe beginnings and ends of the curves. The mileage by year schedules for each subcategory—rather than the aggregated VMT—is used in rulemakings pertaining to fuel

economy.

The linear regression model for the aggregated light truck VMT was presented earlier on page 17 of this report.

6 The aggregated VMT schedule under the column heading in Table 11, “All Light Trucks,” is created by combing all three sub-categories of light trucks (Pic kups, SUVs and Vans) into one single group. This aggregated light truck VMT schedule also appears in Table 6 (p. 19), Table 8 (p. 25) and Tables 10a-10c (pp. 31-33).36 Table 11 Average Annual Miles Driven by Age for Light-Duty Vehicles (estimated values from equations fitted to data from 2002 NHTS) Light Trucks Age Passenger Cars All Light Trucks Pickups SUVs Vans

1 14,231 16,085 16,869 16,270 16,321 2 13,961 15,782 16,270 15,786 15,951 3 13,669 15,442 15,681 15,316 15,555 4 13,357 15,069 15,105 14,859 15,135 5 13,028 14,667 14,541 14,417 14,693 6 12,683 14,239 13,990 13,988 14,234 7 12,325 13,790 13,453 13,571 13,759 8 11,956 13,323 12,931 13,167 13,271 9 11,578 12,844 12,424 12,775 12,774 10 11,193 12,356 11,932 12,395 12,270 11 10,804 11,863 11,457 12,025 11,763 12 10,413 11,369 10,999 11,667 11,255 13 10,022 10,879 10,559 11,320 10,750 14 9,633 10,396 10,138 10,983 10,249 15 9,249 9,924 9,736 10,656 9,757 16 8,871 9,468 9,353 10,338 9,275 17 8,502 9,032 8,991 10,031 8,808 18 8,144 8,619 8,650 9,732 8,358 19 7,799 8,234 8,331 9,442 7,927 20 7,469 7,881 8,034 9,161 7,519 21 7,157 7,565 7,761 8,888 7,137 22 6,866 7,288 7,511 8,623 6,783 23 6,596 7,055 7,285 8,367 6,461 24 6,350 6,871 7,085 8,118 6,174 25 6,131 6,739 6,911 7,876 5,923
26 6,663 6,762 7,641 5,714
27 6,648 6,641 7,414 5,547
28 6,648 6,548 7,193 5,427
29 6,648 6,483 6,979 5,355
30+ 6,648 6,448 6,771 5,3363702,0004,0006,0008,00010,00012,00014,00016,00018,0001 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30Passenger CarsAll Light TrucksPickupsSUVsVansVehicle Age (years)

Average Annual Miles Driven (miles)Figure 7Average Annual Miles Driven by Different Classes of Light Trucksby Vehicle Age