Light-Duty Automotive Technology,
Carbon Dioxide Emissions, and Fuel
1975 Through 2012
Appendix A
Database Details and Calculation Methods
This technical report does not necessarily represent final EPA decisions or
positions. It is intended to present technical analysis of issues using data
that 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 developments.
Economy Trends:
Transportation and Climate Division
Office of Transportation and Air Quality
U.S. Environmental Protection Agency
NOTICE
United States
Environmental Protection
Agency
EPA-420-R-13-001A
March 2013

-------
Harmonically Averaging Fuel Economy Values
Dimensionally, fuel economy is miles divided by gallons. Then, presented with more than one
fuel economy value, an approach to averaging the values is to compute the result by determining the total
miles traveled and dividing that by the total gallons used.
Example: A motorist's fuel economy log for May shows that 704 miles were accumulated around
town in which the fuel economy was 16 mpg, and one 216 mile highway trip was taken on which the fuel
economy was 24 mpg. What is the average fuel economy for May?
The total miles are 704 + 216 = 920. The total gallons thus are 704 / 16 = 44 plus
216 / 24 = 9 or a total of 53 gallons. The average mpg is 920 / 53 = 17.4 mpg. Notice that the arithmetic
average of the two fuel economy values (16 + 24) / 2 = 20 mpg gives an individual result that is higher
than the total miles/total gallons result.
Even if the around-town miles traveled and the highway trip miles traveled were the same (460
miles), the average fuel economy would not be 20; it would be 19.2 mpg. This is because in the total
miles/total gallons approach, fuel consumption is arithmetically averaged, but fuel economy is
harmonically averaged, so for the second example (equal trip distances), the calculation would be:
Average MPG =
(- + -
V16 24
)
which is the same as arithmetically averaging the two fuel consumption values.
A specific example of this type of averaging approach is shown in the calculation of the overall
average fuel economy using the EPA "city" (MPGc) and EPA "highway" (MPGh) fuel economy values.
Total Miles
Average MPG =
Total Gallons
Total Miles
City Gallons + Highway Gallons
Total Miles
/ City Miles Highway Miles \
\ City MPG Highway MPG )
Now, if city miles are 55 percent of total miles and highway miles are the remaining 45 percent,
after dividing by total miles,
A-l

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Average MPG =	^
¦ +
MPGC ' MPGhj
and this average mpg would represent a composite mpg value based on the 55% city/45% highway
driving in this example. This 55% city/45% highway weighting is the metric in this report for laboratory
composite fuel economy values.
The same approach can be used when the average mpg of a group of vehicles with different mpg
values is to be calculated. Suppose a fleet of 100,000 vehicles is made up of two classes, one of 70,000
vehicles whose fuel economy is 10 mpg and the other of 30,000 vehicles whose fuel economy is 14 mpg.
Each vehicle in the fleet is assumed to travel the same number of miles (M),
Total Miles = 100,000 M
70,000 M 30,000 M
Total Gallons =	1	
10	14
and the average fuel economy is:
1
Average Fuel Economy = » „—» » = 10.9 mpg
(tc+ti)
where .7 and .3 are the relative shares of each vehicle class in the fleet. Notice that, again, the arithmetic
average of the class fuel economy values (10 + 14)/2 =12 mpg is higher.
In general, some form of a weighted harmonic mean must be used when averaging different fuel
economy values in order to maintain mathematical integrity.
While fuel economy values (in miles per gallon) must be harmonically averaged to maintain
mathematical integrity, fuel consumption values (in gallons per mile) and carbon dioxide emissions
values (in grams per mile) can be arithmetically averaged.
A-2

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Estimated and Final Production Data
Table A-l compares average laboratory 55/45 fuel economy for model years 1998 through 2012
at three points in time:
(1)	an initial estimate determined early in the model year using projected production;
(2)	for some years, a revised estimate determined by using trade publication sales data
that were obtained after the end of each model year, but before the final CAFE data were
submitted by automakers to EPA; and
(3)	final fuel economy values determined from CAFE compliance data provided by the
manufacturers to EPA after the end of the model year.
Historically, the final car plus truck laboratory 55/45 fuel economy values have generally varied
from 0.5 mpg lower to 0.6 mpg higher compared to the original estimates based exclusively on projected
production. But, MY2009 was a very unusual year in this regard. The final car plus truck laboratory
55/45 value for MY2009 was 1.8 mpg higher than the initial estimate for 2009, due to the market turmoil
in MY2009. The final car plus truck adjusted fuel economy value for MY2009 was 1.3 mpg higher than
the initial estimate. For MY 2011, the final car plus truck laboratory values were 0.5 mpg lower than the
initial estimates in last year's report.
The individual EPA car, and truck, fuel economy values shown in Table A-l for years prior to
MY 2011 differ from the values found elsewhere in this report. Beginning with the 2011 report, EPA
reclassified most small, 2 wheel drive SUVs from trucks to cars for the entire database. This reflects a
regulatory change made by NHTSA for CAFE standards beginning in MY 2011 and which will apply for
the joint EPA/NHTSA greenhouse gas emissions and CAFE standards that have been finalized for MY
2012-2025. These changes were not in effect for years prior to MY 2011, and accordingly, the individual
car and truck fuel economy values prior to MY 2011 are based on the previous car and truck definitions.
To enable a comparison with the initial estimates made for this series of reports, the individual car and
truck values in table A-l were calculated using the previous car and truck definitions, which is not
consistent with the rest of this report. While the individual car and truck numbers in Table A-l are
unique, the car and truck definitions do not affect the overall (car plus truck) fuel economy values, which
are consistent with the rest of this report.
A-3

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Table A-l
Comparison of Laboratory 55/45 MPG

Model
Year
Initial
Estimate
Revised
Estimate
Final
Value
Cars
1998
28.6
28.6
28.5

1999
28.1
28.2
28.1

2000
28.1
28.3
28.2

2001
28.3
28.3
28.4

2002
28.5
28.5
28.6

2003
29.0
28.9
28.9

2004
28.7
28.9
28.9

2005
28.9
29.2
29.5

2006
28.8
29.2
29.2

2007
29.4
30.3
30.3

2008
30.3

30.5

2009
30.9

32.1

2010
32.7

32.3

2011
32.8

32.3

2012
34.6


Trucks
1998
20.6
20.6
20.9

1999
20.3
20.4
20.5

2000
20.5
20.5
20.8

2001
20.3
20.4
20.6

2002
20.4
20.3
20.6

2003
20.8
20.9
20.9

2004
20.9
20.9
20.8

2005
21.3
21.2
21.4

2006
21.5
21.9
21.8

2007
22.1
22.1
22.1

2008
22.5

22.7

2009
22.9

23.8

2010
23.8

23.4

2011
23.6

23.9

2012
24.3


Both
1998
24.4
24.4
24.5

1999
23.8
24.0
24.1

2000
24.0
23.9
24.3

2001
23.9
24.0
24.2

2002
24.0
23.9
24.1

2003
24.4
24.2
24.3

2004
24.4
24.4
24.0

2005
24.6
24.6
24.8

2006
24.6
25.3
25.2

2007
25.3
25.7
25.8

2008
26.0

26.3

2009
26.4

28.2

2010
28.3

28.4

2011
28.6

28.1

2012
30.0


A-4

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Use of 3-Year Moving Averages
Use of the three-year moving averages, which effectively smoothes the trends, results in an
improvement in discriminating real trends from what might be relatively small year-to-year variations in
the data. For this report, as shown in Table A-2 (laboratory) and Table A-3 (adjusted), these three-year
moving averages are tabulated at the midpoint. For example, the midpoint for model years 2010, 2011,
and 2012 is MY2011.
Table A-2
Light-Duty Vehicle Laboratory Fuel Economy and Truck Sales Fraction
Model
Year
Actual Data
55/45 Fuel Economy
Car Truck Both
Truck
Production
Fraction
Three-Year Moving Average
Truck
55/45 Fuel Economy Production
Car Truck Both Fraction
1975
15.8
13.7
15.3
19.3%




1976
17.5
14.4
16.7
21.1%
17.2
14.6
16.6
20.1%
1977
18.3
15.6
17.7
19.9%
18.5
15.1
17.7
21.2%
1978
19.9
15.3
18.6
22.5%
19.5
15.2
18.3
21.5%
1979
20.2
14.7
18.7
22.1%
21.2
16.2
19.9
20.4%
1980
23.5
18.6
22.5
16.5%
23.0
17.8
21.8
18.6%
1981
25.1
20.1
24.1
17.2%
24.9
19.7
23.8
17.8%
1982
26.0
20.5
24.7
19.5%
25.7
20.5
24.5
19.6%
1983
25.9
20.8
24.6
22.0%
26.1
20.6
24.6
21.7%
1984
26.3
20.4
24.6
23.5%
26.4
20.6
24.7
23.4%
1985
26.9
20.5
25.0
24.8%
27.0
20.8
25.1
25.4%
1986
27.9
21.4
25.7
27.9%
27.6
21.2
25.5
26.6%
1987
28.0
21.6
25.9
27.2%
28.1
21.4
25.8
28.1%
1988
28.5
21.1
25.9
29.1%
28.2
21.2
25.8
28.7%
1989
28.1
20.9
25.4
29.9%
28.1
20.9
25.5
29.6%
1990
27.7
20.7
25.2
29.6%
27.9
20.9
25.3
30.0%
1991
27.8
21.2
25.4
30.4%
27.6
20.9
25.2
30.5%
1992
27.4
20.8
24.9
31.4%
27.6
21.0
25.1
31.4%
1993
27.6
21.0
25.1
32.4%
27.6
20.8
24.8
34.0%
1994
27.7
20.7
24.6
38.1%
27.8
20.7
24.8
35.7%
1995
28.1
20.5
24.7
36.5%
28.0
20.6
24.7
37.5%
1996
28.0
20.8
24.8
37.8%
28.1
20.6
24.7
38.1%
1997
28.2
20.5
24.5
39.9%
28.1
20.7
24.6
39.8%
1998
28.1
20.8
24.5
41.7%
28.0
20.5
24.4
41.1%
1999
27.8
20.3
24.1
41.7%
27.9
20.6
24.3
41.6%
2000
27.7
20.7
24.3
41.2%
27.8
20.4
24.2
41.4%
2001
27.9
20.3
24.2
41.4%
28.0
20.4
24.2
42.4%
2002
28.3
20.3
24.1
44.7%
28.3
20.4
24.2
44.1%
2003
28.7
20.7
24.3
46.1%
28.5
20.5
24.1
46.3%
2004
28.5
20.5
24.0
48.0%
28.8
20.7
24.4
46.2%
2005
29.1
21.0
24.8
44.4%
28.8
21.0
24.7
44.8%
2006
28.9
21.4
25.2
42.1%
29.3
21.3
25.3
42.5%
2007
29.8
21.6
25.8
41.1%
29.6
21.7
25.7
41.3%
2008
30.1
22.2
26.3
40.7%
30.5
22.3
26.7
38.2%
2009
31.6
23.1
28.2
33.0%
31.4
22.9
27.6
37.0%
2010
32.6
23.4
28.4
37.3%
32.1
23.5
28.2
37.5%
2011
32.3
23.9
28.1
42.2%
33.1
23.9
28.8
38.5%
2012
34.6
24.3
30.0
36.1%




A-5

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Year
1975
1976
1977
1978
1979
1980
1981
1982
1983
1984
1985
1986
1987
1988
1989
1990
1991
1992
1993
1994
1995
1996
1997
1998
1999
2000
2001
2002
2003
2004
2005
2006
2007
2008
2009
2010
2011
2012
Table A-3
Light-Duty Vehicle Adjusted Fuel Economy
Actual Data
City
Highway
Composite
City
Highway
Compos
12.3
15.2
13.5



13.7
16.6
14.9
13.5
16.4
14.6
14.4
17.4
15.6
14.5
17.7
15.8
15.5
19.1
16.9
15.3
18.5
16.6
15.9
19.2
17.2
16.6
20.3
18.1
18.3
22.6
20.0
17.9
22.0
19.6
19.6
24.2
21.4
19.3
24.1
21.2
20.1
25.5
22.2
19.9
25.1
21.9
19.9
25.5
22.1
20.1
25.6
22.2
20.2
25.9
22.4
20.2
26.0
22.5
20.6
26.7
23.0
20.7
26.7
23.0
21.2
27.6
23.7
21.0
27.3
23.5
21.2
27.7
23.8
21.2
27.8
23.8
21.4
28.1
24.1
21.1
27.9
23.8
20.8
27.8
23.6
20.9
27.8
23.7
20.4
27.4
23.3
20.5
27.5
23.4
20.4
27.4
23.3
20.2
27.3
23.1
19.8
27.2
22.9
20.0
27.3
23.0
19.9
27.3
23.0
19.8
27.3
23.0
19.8
27.4
23.0
19.9
27.5
23.1
19.9
27.9
23.3
19.8
27.6
23.1
19.7
27.6
23.1
19.7
27.7
23.2
19.7
27.6
23.2
19.6
27.6
23.1
19.5
27.5
23.0
19.4
27.4
23.0
19.2
27.0
22.7
19.2
27.1
22.7
19.0
26.7
22.5
19.1
26.8
22.6
19.1
26.7
22.6
19.1
26.8
22.6
19.2
26.8
22.8
19.2
26.9
22.8
19.3
27.1
23.0
19.2
27.0
22.9
19.1
27.0
22.9
19.2
27.1
23.0
19.4
27.2
23.1
19.2
27.1
23.0
19.2
27.1
23.0
19.5
27.3
23.3
19.8
27.8
23.7
19.7
27.6
23.5
20.0
28.0
23.9
20.3
28.3
24.2
21.0
29.2
25.0
20.9
29.0
24.9
21.7
29.9
25.7
21.3
29.7
25.4
21.3
30.1
25.6
22.0
30.6
26.2
22.9
31.8
27.3



Three-Year Moving Average
A-6

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A-7

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Table A-3
Light-Duty Vehicle Adjusted Fuel Economy
Trucks
Model
Year
City
Actual Data
Highway
Composite
Three-Year Moving Average
City Highway Composite
1975
10.9
12.7
11.6



1976
11.6
13.2
12.2
11.7
13.3
12.4
1977
12.7
14.2
13.3
12.2
13.7
12.8
1978
12.4
13.7
12.9
12.4
13.6
12.9
1979
12.1
13.1
12.5
13.1
14.6
13.7
1980
14.8
17.1
15.8
14.3
16.3
15.1
1981
16.0
18.6
17.1
15.7
18.3
16.8
1982
16.3
19.0
17.4
16.2
19.1
17.4
1983
16.5
19.6
17.7
16.3
19.3
17.5
1984
16.1
19.3
17.4
16.3
19.4
17.5
1985
16.2
19.3
17.5
16.4
19.6
17.7
1986
16.8
20.1
18.2
16.6
20.0
18.0
1987
16.8
20.4
18.3
16.6
20.2
18.1
1988
16.2
20.1
17.8
16.3
20.1
17.9
1989
15.9
19.8
17.6
15.9
19.9
17.6
1990
15.6
19.8
17.4
15.8
19.9
17.6
1991
15.9
20.2
17.8
15.7
20.0
17.5
1992
15.4
19.9
17.3
15.6
20.1
17.5
1993
15.5
20.1
17.5
15.4
19.9
17.3
1994
15.2
19.6
17.2
15.2
19.7
17.2
1995
14.9
19.4
17.0
15.1
19.6
17.1
1996
15.0
19.8
17.2
14.9
19.5
17.0
1997
14.7
19.4
16.8
14.9
19.6
17.0
1998
14.8
19.7
17.1
14.7
19.4
16.8
1999
14.5
19.1
16.6
14.6
19.4
16.8
2000
14.7
19.3
16.8
14.5
19.1
16.7
2001
14.4
18.8
16.5
14.4
19.0
16.6
2002
14.3
18.8
16.5
14.3
18.9
16.6
2003
14.4
19.1
16.7
14.3
19.0
16.6
2004
14.2
18.9
16.5
14.3
19.2
16.7
2005
14.4
19.5
16.9
14.4
19.4
16.9
2006
14.6
19.7
17.2
14.6
19.7
17.1
2007
14.8
20.0
17.4
14.8
20.1
17.4
2008
15.1
20.5
17.8
15.2
20.6
17.9
2009
15.7
21.4
18.5
15.6
21.2
18.4
2010
15.9
21.7
18.8
16.0
21.7
18.8
2011
16.2
22.1
19.1
16.2
22.1
19.1
2012
16.4
22.5
19.4



A-8

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Table A-3
Light-Duty Vehicle Adjusted Fuel Economy
Cars and Trucks
Model
Year
City
Actual Data
Highway
Composite
Three-Year Moving Average
City Highway Composite
1975
12.0
14.6
13.1



1976
13.2
15.7
14.2
13.1
15.7
14.1
1977
14.0
16.6
15.1
14.0
16.6
15.0
1978
14.7
17.5
15.8
14.5
17.2
15.6
1979
14.9
17.4
15.9
15.7
18.8
17.0
1980
17.6
21.5
19.2
17.1
20.6
18.5
1981
18.8
23.0
20.5
18.6
22.8
20.3
1982
19.2
23.9
21.1
19.0
23.6
20.8
1983
19.0
23.9
21.0
19.1
23.9
21.0
1984
19.1
24.0
21.0
19.1
24.1
21.1
1985
19.3
24.4
21.3
19.4
24.5
21.4
1986
19.8
25.0
21.8
19.6
24.9
21.7
1987
19.8
25.3
22.0
19.7
25.2
21.9
1988
19.6
25.2
21.9
19.5
25.1
21.8
1989
19.1
24.8
21.4
19.1
24.9
21.5
1990
18.7
24.6
21.2
18.9
24.7
21.3
1991
18.8
24.7
21.3
18.6
24.6
21.1
1992
18.2
24.4
20.8
18.4
24.5
21.0
1993
18.2
24.4
20.9
18.1
24.2
20.7
1994
17.8
23.8
20.4
17.9
24.1
20.6
1995
17.7
24.1
20.5
17.7
24.0
20.4
1996
17.6
24.0
20.4
17.6
23.9
20.4
1997
17.4
23.6
20.2
17.4
23.8
20.2
1998
17.2
23.6
20.1
17.2
23.4
20.0
1999
16.9
23.0
19.7
17.0
23.2
19.9
2000
16.9
23.0
19.8
16.9
23.0
19.7
2001
16.8
22.8
19.6
16.8
22.8
19.6
2002
16.6
22.5
19.5
16.7
22.7
19.6
2003
16.7
22.7
19.6
16.6
22.6
19.4
2004
16.3
22.4
19.3
16.6
22.7
19.6
2005
16.8
23.1
19.9
16.7
23.0
19.8
2006
17.0
23.4
20.1
17.1
23.5
20.2
2007
17.4
24.0
20.6
17.3
23.9
20.6
2008
17.7
24.4
21.0
18.0
24.8
21.3
2009
18.9
26.0
22.4
18.6
25.5
22.0
2010
19.1
26.2
22.6
18.9
26.1
22.5
2011
18.8
26.1
22.4
19.3
26.7
22.9
2012
20.0
27.7
23.8



A-9

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Methodology for Adjusted Fuel Economy Values
for Model Years 1986-2012
On December 27, 2006, EPA published regulations that changed the methodology for calculating
the city and highway fuel economy label estimates for new passenger cars and light trucks (71 Federal
Register 77872). This revised methodology provides fuel economy estimates to consumers that better
reflect real world fuel economy. The methodology incorporates test data that directly account for several
important factors that affect fuel economy in the real world, such as high speeds, aggressive accelerations
and decelerations, the use of air conditioning, and operation in cold temperatures, and indirectly account
for a number of other factors that are not reflected in EPA laboratory test data such as changing fuel
composition, road conditions, etc.
These vehicle fuel economy label changes were implemented beginning with the 2008 model
year. For model years 2008-2010, manufacturers had two options for calculating city and highway fuel
economy labels: 1) use vehicle-specific "5-cycle" (Federal Test Procedure for urban stop-and-go driving,
Highway Fuel Economy Test for rural driving, US06 test for high speeds and aggressive driving, SC03
test for air conditioning operation, and cold FTP test for cold temperature operation) fuel economy test
data in "composite" equations that calculate vehicle-specific city and highway fuel economy values using
weighting factors for data from each of the 5 EPA test cycles, or 2) use an industry-average "mpg-based"
method to derive 5-cycle values, which yields mpg-based adjustments based on a regression of recent 5-
cycle fuel economy data for the industry as a whole, and applied to "2-cycle" fuel economy test results.
Beginning with MY 2011, manufacturers are required to perform an evaluation using 5-cycle tests
conducted for vehicle emissions certification that determines whether the models represented by the
certification vehicle are eligible to use the less resource-intensive mpg-based method for determining
adjusted fuel economy values. The evaluation consists of a comparison of 5-cycle and mpg-based 2-cycle
fuel economy values to determine whether the mpg-based method achieves results comparable to the 5-
cycle method. If the evaluation finds that the 5-cycle method yields significantly lower fuel economy
estimates than the derived 5-cycle method, then the manufacturer is required to use the 5-cycle method
for all models represented by the emission certification vehicle. Of course, a manufacturer may use the
full 5-cycle method for any vehicles for which it is not required if they believe it produces better fuel
economy results. Although this required evaluation has resulted in more models using the 5-cycle
method, they are still in the minority. In the 2010 model year, before this evaluation was required, about
seven percent of models used the more complex and labor-intensive method, but two years later, in the
2012 model year, this fraction has doubled to about 14 percent. For more details on the derivation of
these options, the specific equations that allow an automaker to calculate new label values using either the
vehicle-specific 5-cycle test data or the industry-average mpg-based derived 5-cycle approach, and the
impact of these changes on average fuel economy label values, see the Preamble to the new regulations
(71 Federal Register 77881-77893).
Beginning with the 2007 Trends report, EPA has made significant changes in how adjusted (ADJ)
fuel economy values for model years 1986 through 2012 are calculated to reflect the revised EPA fuel
economy label methodology. These changes affect every table and figure in this report that involve
adjusted fuel economy data. Accordingly, adjusted fuel economy values for 1986 and later model years
should not be compared with the corresponding values from pre-2007 reports in this series. Specifically,
the adjusted fuel economy values for 1986-2012 in this report differ from those in pre-2007 reports as
explained below.
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• For model years 2005-2012, EPA calculates adjusted fuel economy values for most of the
individual models in the fuel economy trends database using the following city and highway
"mpg-based" equations from the EPA fuel economy labeling rulemaking:
New ADJ CITY = 	-r^
0.003259 + LAB CITY
New ADJ HWY = 	TTJZT
0.001376+ 13466
LAB HWY
The above equations are not used if a manufacturer chooses the option of providing vehicle-
specific 5-cycle test data for an individual model. In that case, the adjusted fuel economy
values are calculated using equations with weighting factors for the vehicle-specific data
from the 5-cycle tests.
Calculating fleetwide adjusted city and highway fuel economy values for a given model year
requires a harmonic, production-weighted average of all of the adjusted city and highway fuel
economy values for individual models.
The above equations yield a greater downward adjustment for higher fuel economy vehicles
than for lower fuel economy vehicles. For example, compared to the older fuel economy
label methodology, a 15 mpg city value will be reduced by an additional 10%, while a 50
mpg city value will be reduced by an additional 18%. Likewise, a 20 mpg highway value
will be reduced by an additional 7%, while a 50 mpg highway value will be reduced by an
additional 11%. EPA projected an overall average fleetwide adjustment of 11% lower for
city fuel economy and 8% lower for highway fuel economy, beyond that in the older label
adjustment methodology that has been used in pre-2007 reports in this series. These factors
can be used to convert older adjusted fuel economy values to the newer adjusted fuel
economy values for the current fleet as a whole, but would not be appropriate factors to use
for individual models or for a future fleet with different mpg characteristics.
This report seldom uses separate city and highway fuel economy values, but typically uses
the composite city/highway fuel economy value. Pre-2007 reports used a 55% city/45%
highway weighting for adjusted composite fuel economy values, the same weighting used for
laboratory composite values and for the CAFE compliance program. The analysis of real
world driving activity underlying the newer fuel economy label methodology assumed a
"speed cutpoint" of 45 miles per hour to differentiate between city and highway driving (71
Federal Register 77904). Based on this speed cutpoint, the correct weighting for correlating
the new city and highway fuel economy values with real world driving, on a miles driven
basis, is 43% city/57% highway. Accordingly, the 43% city/57% highway weighting is now
used for all adjusted composite city/highway fuel economy values in this report beginning
with the 2005 model year (note that the historic 55% city/45% highway weighting is still used
for both CAFE compliance and fuel economy labels).
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The appropriate fleetwide factors to convert laboratory or older adjusted fuel economy values
to the newer adjusted fuel economy values are dependent on the city fuel economy-to-
highway fuel economy ratios in the fleet. On average, for the current fleet, combining the
11% lower adjustment for city fuel economy, the 8% lower adjustment for highway fuel
economy, and the shift to the 43% city/57% highway weighting, the newer adjustment for
city/highway composite fuel economy values is 7% lower than that used in the older label
adjustment methodology. This 7% lower value is the average impact for a fleet with the mpg
and city fuel economy-to-highway fuel economy characteristics of the current MY 2012 fleet,
and would not be the appropriate value for individual models, partial fleet segments, or for
past or future fleets with different mpg and city fuel economy-to-highway fuel economy
distributions.
• For model years 1986 through 2004, EPA calculates adjusted fuel economy values based on
the assumption that the impacts of the factors that have led to lower real world fuel economy
have occurred in a gradual (i.e., linear) manner over the 20 years from 1986 through 2005.
On April 6, 1984, EPA published regulations that established the older fuel economy label
adjustment factors of 0.9 for city fuel economy and 0.78 for highway fuel economy that took
effect for model year 1985 vehicles (49 Federal Register 13832). EPA believes that these
adjustment factors were appropriate through the 1985 model year. EPA has not attempted to
perform a year-by-year analysis to determine the extent to which the many relevant factors
(including highway speed limits, more aggressive driving, vehicle horsepower-to-weight
ratio, suburbanization, congestion, use of air conditioning, gasoline composition, et al) that
have affected real world fuel economy since 1985 have changed over time. Rather, EPA has
made the simplifying, but we think reasonable, assumption that the collective impact of these
changes has been a linearly increasing impact over the 20 years from 1986 through 2005.
Using the equations shown above for individual models, EPA has assumed 1/20 of the fully
phased-in downward adjustment for city and highway values would be reflected in the 1986
data, 2/20 of this adjustment would be reflected in the 1987 data, etc., up to 19/20 of this
adjustment in 2004 and the full adjustment in 2005 and later years. Likewise, EPA has
assumed the 55/45 city/highway weighting changes to a 43/57 city/highway weighting in a
linear fashion over the 1986 to 2005 time period as well. The average fleetwide composite
city/highway fuel economy values for 2005 were projected to be , on average, about 6%
lower than the composite city/highway fuel economy value calculated with the older
adjustment factors.
To generate precise adjusted city, highway, or composite fuel economy values for individual
models or for future fleetwide averages with different mpg or city fuel economy-to-highway fuel
economy ratios than the current fleet, it is essential to use the above equations to calculate adjusted city
and highway fuel economy values for individual models, then use the 43% city/57% highway weighting
to generate an adjusted composite fuel economy value for individual models, and then calculate the
harmonically production-weighted average of the individual models to yield the average composite fuel
economy for the fleet as a whole. Alternatively, for a first-order estimate of generic fleetwide factors that
one could use to convert values from the historic fuel economy trends database to the newer adjusted fuel
economy levels, see the factors in Table A-4, which are based on the mpg and city fuel economy-to-
highway fuel economy characteristics of the current fleet. For example, the industry-wide adjusted
composite city/highway fuel economy value for model year 1986 in this year's report, which will be
reported as ADJ COMP, is about .997 (1.0 minus 0.003, where 0.003 equals 0.3%, and the latter is equal
A-12

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to 6% divided by 20) times the adjusted composite city/highway fuel economy value, or ADJ 55/45, from
pre-2007 reports in this series. Likewise, the same industry-wide ADJ COMP value for 1986 can be
approximated by multiplying the laboratory composite 55/45 value for 1986 by 0.851. The industry-wide
ADJ COMP fuel economy values for model years 2005-2011 in this year's report are all equal to 0.80
times the laboratory composite 55/45 values.
It is important to note that the above discussion, as well as all the data in this report, is focused on
new model year vehicle fleets, i.e., the data for a MY2000 vehicle is most directly relevant for that
vehicle operated on the road in calendar year 2000. Because most (though not all) of the real world
factors reflected in this methodology are relatively independent of vehicle design, the best approximation
of the adjusted fuel economy of a used MY2000 vehicle in calendar year 2011 would be to use the 2011
factors in Table A-4.
Table A-5 provides a comparison of adjusted composite fuel economy values, for cars and trucks
combined, using both the older fuel economy label methodology that has been used in pre-2007 reports in
this series as well as the newer fuel economy label methodology described above and used in 2007 and
later reports.
No changes have been made in the way EPA calculates adjusted fuel economy values for 1975-
1985. For these model years, EPA still uses the 0.9 city/0.78 highway fuel economy adjustments
established in 1984, along with the 55% city/45% highway weighting factor. EPA believes that this
methodology was appropriate for the late 1970s and early 1980s and is not making any changes to
adjusted fuel economy values for 1975 through 1985.
No changes have been made in the laboratory (LAB) fuel economy values in this report. The
laboratory city value remains the fuel economy value over the EPA Federal Test Procedure, the laboratory
highway value remains the fuel economy value over the EPA Highway Fuel Economy Test, and the
laboratory 55/45 is a weighted value of these two tests, with a 55% weighting of the Federal Test
Procedure and a 45% weighting of the Highway Fuel Economy Test. The laboratory 55/45 values are
used for CAFE compliance, in conjunction with alternative fuel vehicle credits and test procedure
adjustments. Because the underlying methodology for generating and reporting the laboratory fuel
economy values have not changed since this series began in the mid-1970s, these values provide an
excellent basis with which to compare long-term fuel economy trends from the perspective of vehicle
design, apart from the factors that affect real world fuel economy that are reflected in the adjusted fuel
economy values.
Finally, this same methodology for including real world factors in the adjusted fuel economy
values is also reflected in the adjusted carbon dioxide (C02) emissions data as well. As discussed in
Section IV, EPA back-calculated all C02 emissions values in this report from corresponding fuel
economy values in the historical Trends database. Accordingly, the adjusted C02 emissions values
explicitly account for the above methodology for 1986 and later model years.
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Table A-4
Approximate Factors for Converting Industry-Wide Fuel Economy Values from Previous
Reports to the New Fuel Economy Values in this 2012 Report
Factors to convert	Factors to convert
older ADJ to new ADJ	LABtonewADJ

CITY
HWY
55/45
CITY
HWY
55/45
1975-1985
1.000
1.000
1.000
0.900
0.780
0.854
1986
0.995
0.996
0.997
0.895
0.777
0.851
1987
0.989
0.992
0.994
0.890
0.774
0.849
1998
0.984
0.988
0.991
0.885
0.771
0.846
1989
0.978
0.984
0.988
0.880
0.768
0.843
1990
0.973
0.980
0.985
0.875
0.765
0.841
1991
0.967
0.976
0.982
0.870
0.762
0.838
1992
0.962
0.972
0.979
0.865
0.759
0.835
1993
0.956
0.968
0.976
0.860
0.756
0.832
1994
0.951
0.964
0.973
0.855
0.753
0.830
1995
0.945
0.960
0.970
0.850
0.750
0.827
1996
0.940
0.956
0.967
0.845
0.747
0.824
1997
0.934
0.952
0.964
0.840
0.744
0.822
1998
0.929
0.948
0.961
0.835
0.741
0.819
1999
0.923
0.944
0.958
0.830
0.738
0.816
2000
0.918
0.940
0.955
0.825
0.735
0.814
2001
0.912
0.936
0.952
0.820
0.732
0.811
2002
0.907
0.932
0.949
0.815
0.729
0.808
2003
0.901
0.928
0.946
0.810
0.726
0.805
2004
0.896
0.924
0.943
0.805
0.723
0.803
2005 - 2012
0.890
0.920
0.940
0.800
0.720
0.800
Important Notes for Table A-4:
1.	Multiplying the factors above times the appropriate values from pre-2007 reports approximates the
newer adjusted (ADJ) fuel economy values in this 2012 report. Also, these factors can be used "in
reverse" to convert new adjusted fuel economy values in this report to corresponding old adjusted fuel
economy values or to corresponding laboratory fuel economy values, e.g., dividing an adjusted, combined
city/highway MY 2012 fuel economy value in this report by .940 would yield a corresponding adjusted
fuel economy value based on the methodology used in pre-2007 reports.
2.	These factors are first-order approximations relevant only for industry-wide fuel economy values for
the 1986 through 2012 timeframe.
3.	Precise estimates for individual models require the use of the mpg-based equations for ADJ CITY and
ADJ HWY provided above as well as a linear phase-in, over the 1986 to 2005 time period, for both the
mpg-based equations and the change from a 55/45 city/highway weighting to a 43/57 city/highway
weighting.
4.	These approximations would yield the largest error for individual models or fleets with high mpg
and/or high city fuel economy-to-highway fuel economy ratios.
A-14

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Table A-5
Comparison of "Old" and "New" Adjusted Composite Fuel Economy Values,
for Cars and Trucks Combined, for 2003-2012
Cars and Trucks Combined	
"Old"	"New"
Model Adjusted Adjusted
Year Composite Composite
2003
20.8
19.6
2004
20.5
19.3
2005
21.2
19.9
2006
21.5
20.1
2007
22.0
20.6
2008
22.4
21.0
2009
24.1
22.4
2010
24.3
22.6
2011
24.5
22.8
2012
25.6
23.8
Important Notes for Table A-5:
1.	"Old" adjusted composite fuel economy values are based on the EPA fuel economy label
methodology used in previous reports in this series, i.e., 10% downward city adjustment, 22% downward
highway adjustment, and a 55% city/45% highway weighting factor.
2.	"New" adjusted composite fuel economy values are based on the new EPA fuel economy label
methodology, applicable to MY2011 vehicles and used for the first time in the 2007 report and described
in the previous section.
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Comparison of EPA and NHTSA Data, 1975-2012
Table A-6 compares CAFE performance data reported by the National Highway Traffic Safety
Administration ("Summary of Fuel Economy Performance" report dated October 2, 2012 and available at
www.nhtsa.gov) with the adjusted and unadjusted (laboratory) composite fuel economy data in this
report. The NHTSA values in Table A-6 are generally higher than the EPA laboratory values due to
differences in alternative fuel vehicle credits, test procedure adjustment factors for cars, and, for years
prior to MY 2011, some minor differences in vehicle classification. In recent years for which both
Agencies report final data, the NHTSA values are typically 0.6-1.0 mpg higher than the EPA values due
to these differences. For MY2012, the preliminary NHTSA value is higher than the preliminary EPA
number by 0.6 mpg for cars and 0.7 mpg for trucks. These preliminary projections are based on different
data sets. The EPA value is based on automaker submissions in the spring and summer of 2011 to
support vehicle fuel economy labels. The NHTSA value is based on automaker estimates provided in
mid-model year CAFE reports later in 2011. Final MY2012 results will be reported in next year's report.
The EPA car and truck fuel economy values shown in Table A-6 for years prior to MY 2011
differ from the values found elsewhere in this report. Beginning with the 2011 report, EPA reclassified
most small, 2 wheel drive SUVs from trucks to cars for the entire MY 1975-2012 database. This reflects
a regulatory change made by NHTSA for CAFE standards beginning in MY 2011 and which will apply
for the joint EPA/NHTSA greenhouse gas emissions and CAFE standards that have been finalized for
MY 2012-2025. These changes were not in effect for years prior to MY 2011, and accordingly NHTSA's
CAFE fuel economy values prior to MY 2011 are based on the previous car and truck definitions. To
enable a comparison to the NHTSA values, the EPA car and truck values in Table A-6 through model
year 2010 were calculated using the previous car and truck definitions, which is not consistent with the
rest of this report. While the individual car and truck numbers in Table A-6 are unique, the car and truck
definitions do not affect the overall (car plus truck)fuel economy values, which are consistent with the
rest of this report.
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Table A-6
EPA Adjusted, Laboratory, and NHTSA CAFE Fuel Economy Values by Model Year



Cars


Trucks


Both Cars and Trucks

Model
EPA
EPA
NHTSA

EPA
EPA
NHTSA

EPA
EPA
NHTSA

Year
Adj.
Unadj.
(CAFE)
Diff.
Adj.
Unadj.
(CAFE)
Diff.
Adj.
Unadj.
(CAFE)
Diff.
1975
13.5
15.8
n/a

11.6
13.7
n/a

13.1
15.3
n/a

1976
14.9
17.5
n/a

12.2
14.4
n/a

14.2
16.7
n/a

1977
15.6
18.3
n/a

13.3
15.6
n/a

15.1
17.7
n/a

1978
16.9
19.9
19.9
0.0
12.9
15.2
n/a

15.8
18.6
19.9
1.3
1979
17.2
20.3
20.3
0.0
12.5
14.7
18.2
3.5
15.9
18.7
20.1
1.4
1980
20.0
23.5
24.3
0.8
15.8
18.6
18.5
-0.1
19.2
22.5
23.1
0.6
1981
21.4
25.1
25.9
0.8
17.1
20.1
20.1

20.5
24.1
24.6
0.5
1982
22.2
26.0
26.6
0.6
17.4
20.5
20.5

21.1
24.7
25.1
0.4
1983
22.1
25.9
26.4
0.5
17.8
20.9
20.7
-0.2
21.0
24.6
24.8
0.2
1984
22.4
26.3
26.9
0.6
17.4
20.5
20.6
0.1
21.0
24.6
25.0
0.4
1985
23.0
27.0
27.6
0.6
17.5
20.6
20.7
0.1
21.3
25.0
25.4
0.4
1986
23.7
27.9
28.2
0.3
18.2
21.4
21.5
0.1
21.8
25.7
25.9
0.2
1987
23.8
28.1
28.5
0.4
18.3
21.6
21.7
0.1
22.0
25.9
26.2
0.3
1988
24.1
28.6
28.8
0.2
17.9
21.2
21.3
0.1
21.9
25.9
26.0
0.1
1989
23.7
28.1
28.4
0.3
17.6
20.9
21.0
0.1
21.4
25.4
25.6
0.2
1990
23.3
27.8
28.0
0.2
17.4
20.7
20.8
0.1
21.2
25.2
25.4
0.2
1991
23.4
28.0
28.4
0.4
17.8
21.3
21.3

21.3
25.4
25.6
0.2
1992
23.1
27.6
27.9
0.3
17.4
20.8
20.8

20.8
24.9
25.1
0.2
1993
23.5
28.2
28.4
0.2
17.5
21.0
21.0

20.9
25.1
25.2
0.1
1994
23.3
28.0
28.3
0.3
17.2
20.8
20.8

20.4
24.6
24.7
0.1
1995
23.4
28.3
28.6
0.3
17.0
20.5
20.5

20.5
24.7
24.9
0.2
1996
23.3
28.3
28.5
0.2
17.2
20.8
20.8

20.4
24.8
24.9
0.1
1997
23.4
28.4
28.7
0.3
17.0
20.6
20.6

20.1
24.5
24.6
0.1
1998
23.4
28.5
28.8
0.3
17.1
20.9
21.0
0.1
20.1
24.5
24.7
0.2
1999
23.0
28.2
28.3
0.1
16.7
20.5
20.9
0.4
19.7
24.1
24.5
0.4
2000
22.9
28.2
28.5
0.3
16.9
20.8
21.3
0.5
19.8
24.3
24.8
0.5
2001
23.0
28.4
28.8
0.4
16.7
20.6
20.9
0.3
19.6
24.2
24.5
0.3
2002
23.1
28.6
29.0
0.4
16.7
20.6
21.4
0.8
19.5
24.1
24.7
0.6
2003
23.2
28.9
29.5
0.6
16.9
20.9
21.8
0.9
19.6
24.3
25.1
0.8
2004
23.1
28.9
29.5
0.6
16.7
20.8
21.5
0.7
19.3
24.0
24.6
0.6
2005
23.5
29.5
30.3
0.8
17.2
21.4
22.1
0.7
19.9
24.8
25.4
0.6
2006
23.3
29.2
30.1
0.9
17.5
21.8
22.5
0.7
20.1
25.2
25.8
0.6
2007
24.1
30.3
31.2
0.9
17.7
22.1
23.1
1.0
20.6
25.8
26.6
0.8
2008
24.3
30.5
31.5
1.0
18.2
22.7
23.6
0.9
21.0
26.3
27.1
0.8
2009
25.4
32.1
32.9
0.8
19.0
23.8
24.8
1.0
22.4
28.2
29.0
0.8
2010
25.8
32.7
33.9
1.2
19.1
23.8
25.2
1.4
22.6
28.4
29.3
0.9
2011
25.6
32.3
33.3
1.0
19.1
23.9
24.6
0.7
22.4
28.1
29.0
0.9
2012
27.3
34.6
35.2

19.4
24.3
25.0

23.8
30.0
30.8

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Comparison of EPA and NHTSA Data for MY2011 by Manufacturer
The primary differences between EPA unadjusted laboratory fuel economy data and NHTSA
CAFE values are flexible fuel vehicle (FFV) credits that are available to manufacturers that produce
vehicles capable of operation on an alternative fuel (generally a blend of 85 percent ethanol and 15
percent gasoline), and test procedure adjustment (TPA) credits that apply to manufacturers of passenger
cars. Any remaining offsets are due to alternative fuel vehicles, which are not included in the overall fuel
economy values provided in this report (see section VIII Alternative Fuel Vehicle Trends, for more
information about alternative fuel vehicles), or due to rounding.
Table A-7 shows a detailed MY2011 comparison, for the eleven highest-volume manufacturers
(excluding Hyundai and Kia), of the EPA laboratory fuel economy values from this report and final
NHTSA CAFE values based on the year end fuel economy report data provided to EPA and NHTSA by
automakers. This table shows how EPA laboratory values, FFV credits, and TPA credits "add up" to
CAFE values.
In order to be consistent with NHTSA CAFE reports, Fiat is excluded from the Chrysler data for
Table A-7, but is included with Chrysler elsewhere in this report.
The FFV and TPA credit values in Table A-7 were obtained directly from EPA's fuel economy
compliance program. The data is from the annual manufacturer Corporate Average Fuel Economy
(CAFE) Reports. The CAFE program recognizes Domestic and Import passenger vehicles separately, so
the passenger car results in Table A-7 are calculated from these categories. The truck FFV credit values
were obtained directly (trucks are not eligible for TPA credits). The combined car and truck FFV and
TPA credits were generated using the car and truck sales. This column is shown for illustrative purposes
only, since there are no CAFE standards for combined cars and trucks.
For MY2011, five manufacturers earned FFV credits for cars and six manufacturers did so for
trucks. All manufacturers were eligible for the TPA credits for cars.
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Table A-7
Comparison of MY2011 EPA Laboratory and Final NHTSA CAFE Values
by Manufacturer
Manufacturer

Passenger Car


Light Truck


Both Cars and Trucks


EPA
FFV
TPA
NHTSA
EPA
FFV
TPA
NHTSA
EPA
FFV
TPA
NHTSA

LAB
Credit
Credit
CAFE
LAB
Credit
Credit
CAFE
LAB
Credit
Credit
CAFE
General Motors
29.8
1.2
0.2
31.3
22.0
1.2
0.0
23.2
25.7
1.2
0.1
27.1
Toyota
35.9
0.0
0.3
36.2
24.9
0.5
0.0
25.4
30.6
0.3
0.1
31.0
Ford
31.2
1.2
0.3
32.7
23.0
1.2
0.0
24.2
26.5
1.2
0.1
27.8
Honda
35.4
0.0
0.4
35.8
26.4
0.0
0.0
26.4
30.4
0.0
0.1
30.5
Chrysler
28.4
1.2
0.2
29.8
23.2
1.2
0.0
24.4
24.2
1.2
0.0
25.4
BMW
29.1
0.0
0.2
29.3
25.3
0.0
0.0
25.3
28.4
0.0
0.2
28.6
Daimler
25.1
1.2
0.2
26.6
21.1
0.0
0.0
21.1
23.7
0.7
0.1
24.6
Mazda
33.4
0.0
0.4
33.8
24.6
0.1
0.0
24.7
31.7
0.0
0.3
31.9
Nissan
33.3
0.0
0.3
34.1
23.8
1.0
0.0
24.8
29.6
0.5
0.2
30.5
Subaru
30.2
0.0
0.2
30.5
30.4
0.0
0.0
30.4
30.4
0.0
0.1
30.4
VW
33.5
0.1
0.2
33.9
27.1
0.0
0.0
27.1
32.1
0.1
0.2
32.3
* Two manufacturers, Hyundai and Kia, are not included in the table above due to a continuing investigation. On
November 2. 2012, EP A announced that Hyundai and Kia would lower their fuel economy estimates for many
vehicle models as the result of an EPA investigation of test data.
A-19

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