[Code of Federal Regulations]
[Title 40, Volume 27]
[Revised as ofJuly 1, 2003]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR600.113-88]
[Page 881-882]
TITLE 40--PROTECTION OF ENVIRONMENT
CHAPTER I--ENVIRONMENTAL PROTECTION AGENCY (CONTINUED)
PART 600--FUEL ECONOMY OF MOTOR VEHICLES--Table of Contents
Subpart B--Fuel Economy Regulations for 1978 and Later Model Year
Automobiles--Test Procedures
Sec. 600.113-88 Fuel economy calculations.
The Administrator will use the calculation procedure set forth in
this paragraph for all official EPA tests. For the 1988 model year,
manufacturers may choose to use this procedure or use the calculation
procedure described in Sec. 600.113-78. However, once a manufacturer
uses this procedure, it must be used for all subsequent tests. This
procedure must be used by manufacturers for 1989 and later model years.
The calculations of the weighted fuel economy values require input of
the weighted grams/mile values for HC, CO and CO2 for both
the city fuel economy test and the highway fuel economy test.
Additionally, for tests of gasoline-fueled vehicles, the specific
gravity, carbon weight fraction and net heating value of the test fuel
must be determined. The city and highway fuel economy values shall be
calculated as specified in this section. A sample appears in appendix II
to this part.
(a) Calculate the weighted grams/mile values for the city fuel
economy test for HC, CO, and CO2 as specified in Sec. 86.144
of this chapter. For tests of gasoline-fueled vehicles, measure and
record the test fuel's properties as specified in paragraph (c) of this
section.
(b)(1) Calculate the mass values for the highway fuel economy test
for HC, CO, and CO2 as specified in paragraph (b) of
Sec. 86.144 of this chapter. For tests of gasoline-fueled vehicles,
measure and record the test fuel's properties as specified in paragraph
(c) of this section.
(2) Calculate the grams/mile values for the highway fuel economy
test for HC, CO, and CO2 by dividing the mass values obtained
in paragraph (b)(1) of this section, by the actual distance traveled,
measured in miles, as specified in paragraph (h) of Sec. 86.135 of this
chapter.
(c) Gasoline test fuel properties shall be determined by analysis of
a fuel sample taken from the fuel supply. A sample shall be taken after
each addition of fresh fuel to the fuel supply. Additionally, the fuel
shall be resampled once a month to account for any fuel property changes
during storage. Less frequent resampling may be permitted if EPA
concludes, on the basis of manufacturer-supplied data, that the
properties of test fuel in the manufacturer's storage facility will
remain stable for a period longer than one month. The fuel samples shall
be analyzed to determine the following fuel properties:
(1) Specific gravity per ASTM D 1298.
(2) Carbon weight fraction per ASTM D 3343.
(3) Net heating value (Btu/lb) per ASTM D 3338.
(d) Calculate the city fuel economy and highway fuel economy from
the grams/mile values for HC, CO, CO2 and, for test of
gasoline-fueled vehicles, the test fuel's specific gravity, carbon
weight fraction and net heating value. The emission values (obtained per
paragraph (a) or (b) of this section, as applicable) used in each
calculation of this section shall be rounded in accordance with
Sec. 86.084-26(a)(6)(iii). The CO2 values (obtained per
paragraph (a) or (b) of this section, as applicable) used in each
calculation of this section shall be rounded to the nearest gram/mile.
The specific gravity and the carbon weight fraction (obtained per
paragraph (c) of this section) shall be recorded using three places to
the right of the decimal point. The net heating
[[Page 882]]
value (obtained per paragraph (c) of this section) shall be recorded to
the nearest whole Btu/lb. These numbers shall be rounded in accordance
with the ``Rounding Off Method'' specified in ASTM E 29-67.
(e) For gasoline-fueled automobiles, the fuel economy in miles per
gallon is to be calculated using the following equation:
mpg=(5174x104xCWFxSG)/
[((CWFxHC)+(0.429xCO))+(0.273xCO2))
x((0.6xSGxNHV)+5471)]
Where:
HC=Grams/mile HC as obtained in paragraph (d) of this section.
CO=Grams/mile CO as obtained in paragraph (d) of this section.
CO2=Grams/mile CO2 as obtained in paragraph (d) of
this section.
CWF=Carbon weight fraction of test fuel as obtained in paragraph (d) of
this section.
NHV=Net heating value by mass of test fuel as obtained in paragraph (D)
of this section.
SG=Specific gravity of test fuel as obtained in paragraph (d) of this
section.
Round the calculated result to the nearest 0.1 miles per gallon.
(f) For diesel automobiles, calculate the fuel economy in miles per
gallon of diesel fuel by dividing 2778 by the sum of three terms:
(1) 0.866 multiplied by HC (in grams/miles as obtained in paragraph
(d) of this section),
(2) 0.429 multiplied by CO (in grams/mile as obtained in paragraph
(d) of this section), and
(3) 0.273 multiplied by CO2 (in grams/mile as obtained in
paragraph (d) of this section).
Round the quotient to the nearest 0.1 mile per gallon.
[51 FR 37851, Oct. 24, 1986]