TRANSPORTATION ENERGY DATA BOOK: EDITION 20 - Center for ...

I
The two earlier studies by the Federal Highway Administration (FHWA) indicate maximum fuel efficiency was
achieved at speeds of 35 to 40 mph. The recent FHWA study indicates greater fuel efficiency at higher speeds.
Note that the 1973 study did not include light trucks.
Table 7.21
Fuel Economy by Speed, 1973,1984, and 1997
(miles per gallon)
Speed 1973” 1984” 1997’
(miles per hour) (13 vehicles) (15 vehicles) (9 vehicles)
15
20
25
30
35
40
45
50
55
60
65
70
75
55-65 mph 12.4%
65-70 mph 8.0%
55-70 mph 19.5%
d
d
d
21.1
21.1
21.1
20.3
19.5
18.5
17.5
16.2
14.9
d
21.1
25.5
30.0
31.8
33.6
33.6
33.5
31.9
30.3
27.6
24.9
22.5
20.0
Fuel economy loss
17.8%
9.6%
25.7%
24.4
27.9
30.5
31.7
31.2
31.0
31.6
32.4
32.4
31.4
29.2
26.8
24.8
9.7%
8.2%
17.1%
Source:
1973- U.S. Department of Transportation, Federal Highway Administration, Office of
Highway Planning, The Effect of Speed on Automobile Gasoline Consumption Rates,
Washington, DC, October 1973.
1984 -U.S. Department of Transportation, Federal Highway Administration, Fuel Consumption and
Emission Values for Traffic Models, Washington, DC, May 1985.
1997 - West, B.H., R.N. McGill, J.W. Hodgson, S.S. Sluder, and D.E. Smith, Development and
Verification ofLight-Duty ModalEmissions andFuel Consumption Valuesfor Traffic Models,
FHWA Report (in press), Washington, DC, April 1997, and additional project data, April
1998.
(Additional resources: wwwfhwa-tsiscom)
“Model years 1970 and earlier automobiles.
“Model years 1981-84 automobiles and light trucks.
‘Model years 1988-97 automobiles and light trucks.
dData are not available.
TRANSPORTATJONENERGYDATABOOIC EDITION~O-2000
7-23