EPA-AA-SDSB-79-12
                         Technical Report
             Prediction of U.S. Annual Fuel Consumption
                    by Passenger Automobiles
                               by
                          Tamara Ward
                         Glenn Thompson
                             NOTICE
Technical Reports do not necessarily represent final EPA decisions
or positions.  They  are  intended  to present  technical  analysis  of
issues using data which  are currently available.   The  purpose  in
the  release of  such reports  is to  facilitate the exchange  of
technical information and to inform the public of  technical devel-
opments which may form the basis  for a  final EPA decision, position
or regulatory action.
             Standards Development and Support Branch
               Emission Control Technology Division
           Office of Mobile  Source Air Pollution Control
                Office of Air, Noise and Radiation
               U.S.  Environmental Protection Agency

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I.   Introduction

     The annual  fuel  consumption of  U.S.  passenger  vehicles  is  an
area of  present  and  increasing concern.   In order to  assess  EPA
programs which may  affect  national  fuel  consumption,  it  is impor-
tant to be able to predict future fuel economy trends and possible
modifications of  these trends.  .

     This report  presents  a  computer model  which  can be  used  to
predict trends in U.S.  passenger vehicle  fuel  consumption.   While
this model  is relatively  simple to  allow easy use,  it  is suffi-
ciently  detailed  to provide  accurate  relative  predictions  of
different fuel conservation strategies.   The model methodology was
developed primarily  to  investigate  the  fuel  consumption implica-
tions  of various applications of  tire technology.   During  the
course of  the model  development  it was  decided  to  present  this
material as a separate report to facilitate use of this material .in
other fuel consumption prediction efforts.

     The. actual  prediction model  used  in  this  is quite  simple.
However,   the  mathematical methodlogy of  the model can  be easily
extended to  address  much more complex applications.   In general,
the limiting condition in using the model will be the availability
of detailed input information.

II.  Discussion

~ "   The development of a useful model requires two tasks:   first,
the model must be chosen,  and  second)  there must  be a  literature
search to provide the necessary model input parameters.   While the
first task may be conceptually more difficult,  the second is often
more  time consuming, and is  essential for applications  of  the
model.   Consequently, both the model and the  development  of cur-
rently  suitable  input  parameters  is discussed  in the  following
subsections.  The final section presents the predicted annual fuel
consumption for  1975 through  1985, and compares the  predicted
values for current years with reported data.

     A.   The Model

     The fuel economy prediction model was chosen as:
         TFCON. = i  (VMIX..)(MIT..)(FC.)                        (1)
              1   j      ^J     1J    J
where:
          TFCON. =  the  total annual fuel  consumed  in the  i
                    year.

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     VMIX.. =  the  vehicle  mix  of j  type  vehicles  in the year i.

     MIT..  =  the  annual vehicle miles traveled by  j  type  vehicles
               in the year i.

     FC.    =  the  average   fuel  consumption  of  j  type  vehicles.

     This model  is  basically the model presented by H.H. Gould  and
A.C. Mallioris of DOT._1_/*   While  the  model is  simple,  it has  great
versatility,  since   the  vehicle mix  paramter   j  can  represent . as
detailed  subdivision of  the  vehicle population  as is  desired.   For
example,  a k subscript  could be  introduced to each  of the  para-
meters VMIX,  MIT  and  FC  to  represent  different  tire types.

     The  fact  that  the  model equation (1) is  so simple, yet  ex-
tremely powerful means that  much  of the information content of  the
model  resides in the values  of  the model paramaters VMIX,  MIT,  and
FC.  The  subsequent  section discusses  how  the values to  these  para-
meters were  chosen  and presents the values used in this  analysis.

     B.   Values of  the Model Parameters

     In this analysis only the vehicle model year was  considered as
a  subdivding parameter  of  the vehicle mixture  parameter,   VMIX.
This  approach  was  chosen  because of  the  difficulty  in  obtaining
more  detailed   information  on  the distribution of  the vehicle
population.. With this choice of the vehicle subdivision parameter,
the quantities  which must be obtained  or  constructed for each of
the  i  years of  interest, are VMIXj.  MIT    and  FC., that is .the
number of vehicles  of model year j existent in  the calendar year i,
the annual  miles traveled  by vehicles of  model year  j  in calendar
year i,  and the average fuel economy of vehicles of  model year j.

     In general, this desired information  is available for the past
.ten  years.   It is  believed that these  data can be  accurately
extrapolated  for  approximately  the same time period  into  the
future.   Therefore,  it was decided to predict  the total  annual fuel
consumption  from the  present time until   1985.   Consequently,  the
required  parameters must be known or estimated  for model years 1978
to 1985,  inclusive.

     1.   The Vehicle Population Distribution

     The  distribution  of vehicles by model year in past  years is
readily  available,  usually  from   data  compiled by R.L. Polk from
state  registration  lists.2j   Table 1  gives the currently  available
model  year distribution.  The first  sub-task then is  to  take this
distribution and use it  to predict the vehicle  population  distribu-
tions  for each year until 1985.  This was   accomplished by  computing
 * Numbers underlines  (!_/)  indicate  references  at the end  of  this
 paper.

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                                                       Table 1

                                         Light-Duty Vehicle Registrations by
                                            Model Year and Calendar Year
                                                      (millions)
Model
Year
1977
1976
1975
1974
1973
1972
1971
1970
1969
1968
1967
1966
1965
1964
1963
1962
1961
Calendar Year
—
—
—
—
—
—
—
4.55
5.50
—
—
—
—
• —
—
5.29
6.60
5.54
—
— :
	
—
—
5.84
7.34
6.62
5.45
j
—
—
—
6.40
7.85
7.31
6.62
5.38
—
—
—
6.23
9.01
7.82
7.30
6.57
5.28
—
—
5.82
8.85
8.94
7.73
7.18
6.40
5.02
*™ ™"
6.18
8.12
8.83
8.93
7.66
7.05
6.18
4.65
6.45
8.92
8.05
8.79
8.85
7.53
6.82
5.80
4.08
9.92
6.28
8.81
7.87
8.53
8.50
7.11
6.26
5.05
3.26
5.92
9.28
8.88
8.80
7.77
8.31
8.17
6.65
5.62
4.27
2.52
7,16
8.91
9.12
8.85
8.59
7.49
7.93
7.58
4.92
4.71
3.34
1.82
7.98
10.15
8.71
8.88
8.61
8.29
7.12
7.33
6.71
4.96
3.69
2.47
1.26
6.43
11.26
10.14
8.62
8.61
8.49
7.93
6.62
6.53
5.71
3.97
2.82
1.81
0.90
4.68
9.76
11.33
10.09
8.54
8.34
8.33
7.55
6.11
4.79
4.82
3.23
2.22
1.40
0.68
6.47
7,68
9.74
11.13
9.87
8.24
7.96
7.77
6.85
5.36
4.88
3.92
2.57
1.74
1.08
0.52
7.17
9.55
7.47
9.59
10.85
9.56
7.86
7-**w
6.96 .
5.85
4.41
3.88
3.02
1.96
1.31
0.81
2.093*
* Registrations of all previous model years.

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                     Table 2

       Average Ratio of Vehicles Surviving
       from One Calendar Year to the Next
               versus Vehicle Age

      Years of
    Vehicle Life               Survival Ratio

       1 to  2                      1.386
       2 to  3                      1.022
       3 to  4                      0.991
       4 to  5                      0.981
       5 to  6                      0.972
       6 to  7                      0.959
       7 to  8                      0.933
       8 to  9                      0.895
       9 to 10                      0.856
      10 to 11                      0.813
      11 to 12                      0.785
      12 to 13                      0.773
      13 to 14                      0.773
      14 to 15                      0.763
      15 to 16                      0.755
All Years Beyond 16                 0.750

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                                   5.
vehicle survival ratios for each succeeding model year and projec-
ting the  new 'vehicle sales  for  each required future model  year.

     First, to  compute  the  survival  ratios,  the  ratio of vehicles
surviving  from  each  year  to the subsequent year was  computed  for
each of  the  years of the  life  of  the vehicle.   For  example,  the
ratio of  1975  vehicles  registered  in 1975 to those  1975 vehicles
registered in 1976 were computed,  as  well  as  1976  vehicles regis-
tered in 1976 and 1977, 1977 vehicles registered  in 1977 and 1978,
etc.  All  of the  ratios for survival  from the first to second year
of vehicle life were  averaged as were the  ratios for each sequen-
tial year.  These average  survival  ratios are given in Table 2,  and
may be conveniently  described as  the survival probability vector.

     It may  be noted that  the first  elements of  the survival
probability vector are greater than one.   This may appear surpris-
ing, however  it  is  a logical  result  of using  registration  data
compiled in June of each year.   For example, assume x 1977 vehicles
were sold  and  registered  prior  to  July  1,  1977,  and  that an addi-
tional y 1977 vehicles x^ere sold and  registered after July 1,  1977.
Neglecting the  destroyed  vehicles,  the  ratio  surviving  until July
1, 1978 would be computed  as (x  + y)/x, which of course, is greater
than 1.0.

     In  general,  a  computation problem  is  incurred because  the
vehicle model  year begins  in  September or October,  the calendar
y_e.ar  starts. January 1,  and the  vehicle registration data  are
reported  as  of July  1.   Since  the  purpose  of this  report  is to
present a  simple  method  for investigating  the relative  aspects of
fuel  economy programs, this 'problem is not treated in  detail.
However, it  is  suggested  that one  approach  to improve the predic-
tion system would be to research quarterly, or monthly, new vehicle
sales, and use  this  information to predict  the vehicle  use in the
first months after the vehicle is sold, but before it is recognized
in the July registration data.

     The survival rate vector can be used to predict the number of
vehicles of  any model year existing  in  a  given  calendar year, if
the number registered in  any  previous calendar  year  is known.
Consequently, the survival  rate vector can be used  to predict the
number of vehicles  present in future years  for  all model  year
vehicles  since  1977.   For model years  later  than  1977,  which was
the last  year  of  available registration  data,  some  method must be
used to predict the new vehicle  sales in  each year.

     Considering  the  available  data,  it  was decided to indirectly
predict  the new  vehicle sales by predicting the total  vehicle
population.  This  approach has  several advantages; first  when
attempting  to  model  annual .fuel  consumption,  the  total  vehicle
population is  a  more important parameter  than new  vehicle sales.
Second,  vehicle  sales vary considerably with  the state of the

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                                Table 3

                 >tal Light-Duty Vehicle Registrations
                         versus Calendar Year

                   Year               Registrations
                                      (in millions)
                   1965                    68.9
                   1966                    71.3
                   1967                    73.0
                   1968                    75.4
                   1969                    78.5
                   1970                    80.4
                   1971                    83.1
                   1972                    86.4
                   1973                    89.8
                   1974                    92.6
                   1975                    95.2
                   1976                    97.8
                   1977                    99.9
                   1978*                  102.8
                   1979*                  105.5
                   1980*                  108.2
                   1981*                  110.9
                   1982*                  113.5
                   1983*                  116.2
                   1984*                  118.9
                   1985*                  121.6
* Predicted.

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                                   7


national economy.  Finally,  predicting the  total vehicle population
minimizes the tendency to accumuate errors  which could occur if new
vehicle sales were predicted.

     Table 3  gives  the available total vehicle population data.2j
These data were  fitted with a  linear regression  to predict total
future vehicle populations.   These predicted future total vehicle
populations are also given in Table 3, while the existing data and
the predicted populations are  plotted  in  Figure  1.

     The survival ratios and the total population data provide the
necessary information  to  predict the  vehicle population distribu-
tion.  Starting  with  the 1977 model year,  the most recent year in
which the  population  distribution  is known, the  survival  ratios
were  used  to  predict the  population distributions for  1977  and
earlier model year vehicles in calendar year 1978.  The sum of all
1978 and earlier model year vehicles was  then computed and subtrac-
ted  from  the total predicted  population for 1978  vehicles.   The
difference between  the total  population  and the vehicles existing
from  previous  years  was assumed to be the 1978 model year sales.
This  process was  then iteratively repeated  for all subsequent
years.  The  resulting  predicted vehicle population matrix is given
in Table 4.

     2.    Annual Vehicle Miles Traveled

     The next required parameter is the number of the average
annual  vehicle  miles traveled as  a  function  of vehicle  age.
Unfortunately, little  recent data  are available on this parameter.
The most frequently cited reference is the U.S. Census Bureau data
from  1970. V   These data are 'presented  in Table  5.   It should be
noted that  the .Census  data  indicate  a  very high  number  of miles
traveled during the first year the  vehicle  is in use.  This implies
that  there is  an  initial period  of  intensive use for new vehicles.
However,  it might only reflect the  manner in which  some of the data
were  obtained.   For  example  if a  vehicle which  was purchased in
March had  accumulated 10,000  miles by the  time is was sampled in
August,  just  after  a  5,000 miles summer  vacation trip,  this could
be  interpreted  as a vehicle accumulating  distance  at  the rate of
20,000 miles per year.   If vehicle  use in the  first  few months
after  purchase  were  more  extensively researched  this  potential
problem could be reduced.

      Since the Census  Bureau data  appeared to have  some anomalies,
such  as  vehicles of some  ages  traveling farther  than newer vehi-
cles,  it  was .decided  to "smooth"  the data  by fitting  it  with  a
linear regression.  This approach had  the additional  advantage that
the  regression  could  be used to predict  the annual vehicle miles
traveled for  vehicles more  than  ten years  old.  The vector of
predicted  annual  miles traveled,  which was used in all subsequent
calculations, is presented in Table 6.

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                           Total Vehicle Registrations
                                     versus
                                  Calendar Year
Vehicle
Registrations
(millions)
120
100 .
 80 -.
60   •
              1965        1970
            Predicted Registrations
                                                ORegistration Data
1975

Year
1980        1985
                                    FIGURE 1

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                                      Table 4

                   Predicted Light-Duty Vehicle Registrations by
                            Model Year and Calendar Year
                                     (millions)
Model
Year
1985
1984
1983
1982
1981
1980
1979
1978
1977
1976
1975
1974
1973
1972
1971
1970
1969
1968
1967
1966
1965
1964
1963
1962
1961
1960
1959
Calendar Year
1975*










4.68
9.76
11.33
10.09
8.54
8.34
8.33
7.55
6.11
5.79
4.82
3.23
2.22
1.40
0.68
0.52
1.74+
1976*









6.47
7.68
9.74
11.13
9.87
8.24 .
7.96
7.77
6.85
5.36
4.88
3.92
2.57
1.74
1.08
0.52
1.94+

1977*








7.17
9.55
7.47
9.59
10.85
9.56
,7.86
7.44
6.96
5.85
4.41
3.88
3.02
1.96
1.31
0.81
2.09+


1978;







8.26
9.95
9.77
7.41
9.41
10.55
9.17
7.33*
6.66
5.96
4.76
3.46
3.00
2.33
1.50
0.99
2.18+



1979






7.86
11.44
10.16
9.67
7.26
9.14
10.11
8.55
6.56
5.70
4.84
3.73
2.68
2.32
1.78
1.13
2.38+




1980





8.19
10.89
11.70
10.75
9.49
7.06
8.77
9.44
7.65
5.62
4.64
3.80
2.89
2.07
1.77
1.34
2.63+





1981




8.29
11.36
11.13
11.59
9.88
9.23
6.77
8.18
8.44
6.55
4.57
3.64
2.94
2.23
1.58
1.33
2.98+






1982



8.43
11.49
11.61
11.03
11.37
9.60
8.85
6.32
7.32
7.23
5.32
3.58
2.81
2.27
1.70
1.19
3.. 24+







1983


8.52
11.68
11.74
11.50
10.82
11.05
9.21
8.25
5.65
6.27
5.88
4.18
2.77
2.17
1.73
1.28
3.32+








1984

8.61
11.81
11.94
11.64
11.28
10.52
10.60
8.59
7.39
4.84
5.09
4.61
3.23
2.14
1.60
1.30
3.46+









1985
8.73
11.94
12.07
11.83
11.42
10.97
10.09
9.89
7.69
6.32
3.93
4.00
3.56
2.50
1.63
1.25
3.57+










* Actual registration data presented for these years.
+ Registrations for all previous years.

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               10
            Table 5

     Average Annual Miles
            versus
          Vehicle Age

  Year of          Miles Traveled
Vehicle Life        (thousands)

     1                  17.5
     2                  16.1
     3                  13.2
     4                  11.4
     5                  11.7
     6                  10.0
     7                  10.3
     8                  8.9
     9                  10.9
    10                  8.0
            Table 6

Predicted Average Annual Miles
            versus
          Vehicle Age

  Year of          Miles Traveled
Vehicle Life         (thousands)

     1                     15.9
     2                     14.9
     3                     14.0
     4                     13.1
     5                     12.2
     6                     11.3
     7                     10.4
     8                      9.5
     9                      8.6
    10                      7.7
    11                      6.8
    12                      5.9
    13                      5.0
    14                      4.0
    15                      3.1
    16                      2.2
 17  and older               1.3

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                                    11
     3.   Vehicle Fuel Consumption by Model  Year

     The EPA data are the best indication of average  annual vehicle
fuel consumption. 4/   These data,  for  both  the EPA city cycle and
the composite city/highway cycle,  are  plotted  versus model year  in
Figure 2.   This plot  shows  that a significant change occurred  in
fuel economy  trends  in 1975, the  first  year of the EPA voluntary
fuel economy  program.  Assuming  current  improvements  in the  fuel
economy of  vehicles  will continue, the future fuel economy  trends
were predicted  from  a  linear regression of  the  data  since  1974.
These  regression  lines are shown  in  Figure 2, as are the current
fuel economy standards for 1978 through 1985.  Since  the regression
lines  of  the composite  city/highway values  are  greater  than the
current standards, while  the city cycle  values  are  less than the
standards,  these  regression  predictions  appear  to be reasonable.

     The  fuel economy prediction model requires the fuel consump-
tion of the vehicles  be known.   For  this  reason  fuel consumptions,
the  reciprocal  of  the fuel  economies,  were  calculated  from the
available data,  and  are presented in  Table 7.  Also presented  in
this table are the predicted fuel economy values  and  the subsequent
predicted fuel  consumptions  for 1979  and  later  model  years.  The
two  fuel  consumption columns  of the table may be conveniently
considered  as the  fuel consumption vectors  for the city cycle and
the composite cycle.

     The  vehicle  population  matrix,  Table   4;  the annual vehicle
miles  traveled  vector, Table 6; and the  fuel  consumption vectors,
Table  7;  complete all of  the  information  necessary to use the fuel
consumption model equation (1)..

     C.   Predictions of Annual Fuel Consumption

Using  the model,  equation (1), the  total   fuel consumed, TFCON.
for each  of the years of  interest  can be computed  from the vehicle
distribution matrix,  VMIX^.  given  in  Table  4, the vehicle  miles
traveled, MIT;.   given in Table  6, _and the fuel consumption,  FC,
given in Table 7.  The results of this calculation are  presented in
Figure 3 and Table 8.

     The  computer program  used  to  perform  the  fuel  consumption
calculation is given in the attachment of this report.   It  should
be noted  that  this program  divides  the miles  traveled during  the
first year of vehicle  life  by 2  prior to  multiplying by the  number
of new  model year vehicles.   This  is  done  because it is assumed
that these vehicles  have, on  the  average,  been  in  service for only
one half of the  year prior  to appearing on the  annual  registration
data list.

     In 1975,  it is estimated that  76.01 billion gallons of fuel
were consumed by passenger cars.5/  Based on this  estimate, predic-

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         12
   Fuel Economy
      versus
Vehicle Model Year
JU
25 -


20 •
Fuel
Economy
(mi/gal)
15 •

10 -
19
D EPA composite cycle fuel
economy results. /
OEPA city cycle fuel economy X^-
results. /
•fcFuel economy standards. / /
/* /
/v\
f / ^ — Predicted composite
•+/ cycle fuel economies
D ,7
D o \.
. o ^ — Predicted city cycle
DO . . . fuel economies.
D D D D D D O
D D
o o n n o
0 ° 0 0 o
°0

65 1970 1975 1980 1985
       Year
     Figure 2

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                                   13
  Year
                                   Table 7

                Average Fuel Economy and Fuel Consumption by
                                  Model Year
City Fuel
 Economy
 (mi/gal)
Pre-1968
1968
1969
1970
1971
1972
1973
1974
1975
1976
1977
1978
1979*
1980
1981
1982
1983
1984
1985
13.6
13.2
13.2
13.1
12.9
12.6
12.3
12.2
13.5
15.4
16.3
17.0
18.6
19.8
21.1
22.3
23.6
24.8
26.0
 City Fuel
Consumption
 (gal/mi)

   0.074
   0.076
   0.076
   0.076
   0.078
   0.079
   0.081
   0.082
   0.074
   0.065
   0.061
   0.059
   0.054
   0.050
   0.047
   0.045
   0.042
   0.040
   0.038
 Composite
City/Highway
Fuel Economy
  (mi/gal)

    15.8
    15.4
    15.4
                                                  15.
                                                  15.
                                                  15.0
                                                  14.5
                                                  14.4
                                                  15.6
                                                  17
                                                  18
                                                  19
                                                  21
                                                  22
                                                  23
                                                  25
                                                  26.6
                                                  27.9
                                                  29.2
 Composite
City/Highway
Fuel Economy
  (gal/mi)

    0.063
    0.065
    0.065
    0.065
    0.066
    0.067
    0.069
    0.069
    0.064
    0.056
    0.054
    0.051
    0.047
    0.044
    0.042
    0.040
    0.038
    0.036
    0.034
* Values for model years past 1978 are predicted  from  a  linear
regression of the data from 1975 through  1978  inclusive.

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                            14
              National Annual Fuel Consumption
80
70. ..
60  ..
50  .-
                                        Predicted  fuel  consumption
                                        using  EPA  city  cycle  fuel
                                        economy values.
 DOT Data on
 annual  fuel
 consumption.
              Predicted fuel consumption
              using EPA composite cycle
              fuel economy values.
  1970
1975
1980

Year
1985
                       FIGURE 3

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                        15
                    Table 8

    Predicted Total Annual Fuel Consumption
Consumption Predicted Using
 City Cycle Fuel Economies
Year (billions of gallons)
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
78.1
77.3
76.1
75.5
74.9
73.3
71.4
69.3
67.0
64.7
62.4
Consumption Predicted Using
  Composite Cycle Values
   (billions of gallons)

            66.5

            65.9

            65.1

            64.7

            64.4

            63.2

            61.8

            60.2

            58.4

            56.6

            54.8

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                                    16
tions using the EPA composite fuel economy values appear to under-
estimate  actual  fuel consumption  by twelve  to  thirteen percent.
Using the urban cycle  fuel economy values in the prediction model
appear to provide better  accuracy.   In this case, the model over-
estimates the annual fuel consumption by about  three percent.  This
is consistent with other observations,  and with the decision to use
only  the  urban  fuel economy results for vehicle labels, beginning
with  the 1979 model year._6/  Using the  urban  fuel consumption, the
predicted values  are  in good  agreement with the  reported data.

III. Conclusion

     The model  predictions agree well  with  reported  data for the
current  years.   It is therefore concluded  that the  prediction
accuracy of  the model  should  be quite good since major changes in
vehicle  usage  are  not  expected in  the  next  ten years.   Even if
unanticipated changes do  occur  in vehicle use, predicted relative
effects  of  different technologies should  still  be valid.   It is
therefore recommended  that the model  be used primarily  for the
prediction of the relative effects of different technologies on the
annual fuel consumption.

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                                      17
                             References

I/   H.H.  Gould and A.C.  Malliaris,  "Highway Fuel  Consumption
~~    Computer Model," Department of Transportation Report, DOT-TSC-
     OST-73-43, April  1974.
2/   R.M.  Lienert   (editor),  "Cars Still  in U.S. Use  by Year
     Models," Automotive News,  Detroit,  Michigan,  July 17,  1978.


3/   H.E.  Strate, "Annual Miles  of  Automobile  Travel,"  Nationwide
~~    Personnal Transportation  Study,  U.S. DOT,  Report No.  2,  1972..
     J.D. Murrell,  "Light-Duty Automotive Fuel Economy ...  . Trends
     Through  1978,"  Society of  Automotive  Engineers,  Paper No.
     780036.
5/   W.F.  Gay,  National Transportation Statistics,  Department of
~    Transportation  Annual  Report,  DOT-TSC-OST-77-68,  1977.


6/   Federal Register,  May  17,  1978 (43 FR 21412).

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              18
             Attachment
Fuel Consumption Prediction Program

-------
 >  .   i     c
 >     2     C
 >     3     C     THUS PROGRAM IS DESIGNED TO CALCULATE THE ESTIMATED TOTAL VEHICLE MILES
 >     4     C     TRAVELLED PER YEAR BY PASSENGER VEHICLES AND TH.E ESTIMATED TOTAL GALLONS
 >     5     C     OF GASOLINE CONSUMED.
 >     6     C
 >     7     C
 >     Q           DIMENSION VEHPOP<27» 11 > » VMILES<30 > r CITYFE<30) rVMT(30> rGASC<30> rSVMTC 11 > »SGASC< 11 >
 >     9     C                                    .     •        '
 >    10     C
 >    11     C     THIS SEQUENCE PRESETS THE ELEMENTS  OF THE ARKAYSr DESIGNATED SVMT AND
 >    12     C     SGASC RESPECTIVELY*  TO BE ASSIGNED  THE VALUE OF ZERO,
 >    13     C
 >    14     C
 >    15           DATA SVMT/11*0./
 >    16   .     .   DATA SGASC/11*0./
 >    17     C
 >    18     C
 >    19     C     THIS SEQUENCE READS  IN THE PREDICTED MATRIX* DESIGNATED VEHPOPr  THE
 >    20     C     ESTIMATED AVERAGE ANNUAL MILES PER  AUTOMOBILE BY YEAR MODELr AND THE
 >    21     C     FUEL ECONOMY STANDARDS FOR PASSENGER VEHICLES,
 >   . 22     C
••>    :.'3     c                                        .
 >    24           READ(5rlOOO)«VEHPOP    25      1000 FORMAT<12X,11FB.O)
 >    26.2    2000 FORMAT
 >    ;:8        50 L-10
 >    'J9     C
 >    30     C                                              .            .       .
 >    31     C     THIS STATEMENT WAS INTRODUCED WITH THE ASSUMPTION THAT A VEHICLE IS
 >    22     C     DRIVEN HALF THE ANNUAL VEHICLE MILES ITS FIR9T YEAR OF VEHICLE LIFE?
 >    33     C     SINCE THE REGISTRATION DATA WERE OBTAINED ON JULY 1 OF EACH YEAR.
 >    34     C
 >    35     C
 >    36           VMILES    37     C

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>    38     C
>    39     C     THE FOLLOWING TWO DO LOOPS SCAN EACH SUCCESSIVE COLUMNf ROW-DY-ROW
>    40     C     AND PERFORM THE FOLLOWING OPERATIONS,
> •   41     C
>    42     C
>    43           DO 20 K=lfll
>    44           DO 10 J=lrl7
>    45           JJ=JH.
>    46     C
>    47     C
>    48     C     THE FOLLOWING EQUATION CALCULATES THE TOTAL ANNUAL MILES TRAVELLED
>    49     C     BY VEHICLES .OF EACH MODEL YEAR IN EACH CALENDAR
>    50     C
>    51     C
>    52           VMT(J)=    53     C
>    54     C
>    55     C     THE FOLLOWING EQUAITON CALCULATES THE GALLONS PF§ GASOLINE CONSUMED
> .56     C     BY VEHICLES OF EACH MODEL YEAR IN EACH CALENDAR YEAR,
>    57     C
>    50     C                      .
>    59        40 GASC    60           SVMTCK)=SVMT
>    61           SGASC=SGASC    62        10 CONTINUE
>    63           L=L-1
>    64        20 CONTINUE
>    65     C
>    66     C
>    67     C     THIS SEQUENCE WRITES OUT THE TOTAL VEHICLE MILES.TRAVELLED AND THE
>    68     C     TOTAL GALLONS OF GASOLINE CONSUMED PER YEAR,
>    69     C
>    70     C
>    71           WRITE(7f3000)
>    72      3000 FORMAT('!')
>    73           WRITE(7r4000>
>    74      4000 FORMAT<10Xr'TOTAL VEHICLE MILES TRAVELLED PER YEAR'»10X»'TOTAL GALLONS OF GASOLINE CONSUMED PER YEAR')
>    75    :       URITE(7r5000)((SVMTrSGASC    76      5000 F.ORMAT('0'F23XrFll,3»40X»F9,3)
>    77           STOP
>    70           END
I

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