[Code of Federal Regulations]
[Title 40, Volume 29]
[Revised as of July 1, 2007]
From the U.S. Government Printing Office via GPO Access
[CITE: 40CFR600.113-93]
[Page 900-903]
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. 600.113-93 Fuel economy calculations.
The Administrator will use the calculation procedure set forth in
this paragraph for all official EPA testing of vehicles fueled with
gasoline, diesel, methanol or natural gas fuel. The calculations of the
weighted fuel economy values require input of the weighted grams/mile
values for total hydrocarbons (HC), carbon monoxide (CO), and carbon
dioxide (CO2); and, additionally for methanol-fueled
automobiles, methanol (CH3 OH) and formaldehyde (HCHO); and
additionally for natural gas-fueled vehicles non-methane hydrocarbons
(NMHC) and methane (CH4) for both the city fuel economy test
and the highway fuel economy test. Additionally, 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; and, additionally for
methanol-fueled automobiles, CH3 OH and HCHO; and
additionally for natural gas-fueled automobiles NMHC and CH4
as specified in Sec. 86.144 of this chapter. 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, and where applicable CH3 OH,
HCHO, NMHC and CH4 as specified in Sec. 86.144(b) of this
chapter. 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, and where applicable CH3
OH, HCHO, NMHC and CH4 by dividing the mass values obtained
in paragraph (b)(1) of this section, by the actual distance traveled,
measured in miles, as specified in Sec. 86.135(h) of this chapter.
(c)(1) 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.
[[Page 901]]
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:
(i) Specific gravity per ASTM D 1298 (Incorporated by reference as
specified in Sec. 600.011-93).
(ii) Carbon weight fraction per ASTM D 3343 (Incorporated by
reference as specified in Sec. 600.011-93).
(iii) Net heating value (Btu/lb) per ASTM D 3338 (Incorporated by
reference as specified in Sec. 600.011-93).
(2) Methanol test fuel shall be analyzed to determine the following
fuel properties:
(i) Specific gravity using either:
(A) ASTM D 1298 (incorporated by reference as specified in Sec.
600.011-93) for the blend or:
(B) ASTM D 1298 (incorporated by reference as specified in Sec.
600.011-93) for the gasoline fuel component and also for the methanol
fuel component and combining as follows:
SG=SGgxvolume fraction gasoline+SGmxvolume
fraction methanol.
(ii)(A) Carbon weight fraction using the following equation:
CWF=CWFgxMFg+0.375xMFm
Where:
CWFg=Carbon weight fraction of gasoline portion of blend per
ASTM D 3343 (incorporated by reference as specified in Sec. 600.011-
93).
MFg=Mass fraction gasoline=(GxSGg)/
(GxSGg+MxSGm)
MFm=Mass fraction methanol=(MxSGm)/
(GxSGg+MxSGm)
Where:
G=Volume fraction gasoline
M=Volume fraction methanol
SGg=Specific gravity of gasoline as measured by ASTM D 1298
(Incorporated by reference as specified in Sec. 600.011-93).
SGm=Specific gravity of methanol as measured by ASTM D 1298
(Incorporated by reference as specified in Sec. 600.011-93).
(B) Upon the approval of the Administrator, other procedures to
measure the carbon weight fraction of the fuel blend may be used if the
manufacturer can show that the procedures are superior to or equally as
accurate as those specified in this paragraph (c)(2)(ii).
(iii) Net heating value (BTU/lb) per ASTM D 240 (Incorporated by
reference as specified in Sec. 600.011-93).
(3) Natural gas test fuel shall be analyzed to determine the
following fuel properties:
(i) Fuel composition per ASTM D 1945-91, Standard Test Method for
Analysis of Natural Gas By Gas Chromatography. This incorporation by
reference was approved by the Director of the Federal Register in
accordance with 5 U.S.C. 552(a) and 1 CFR part 51. Copies may be
obtained from the American Society for Testing and Materials, 1916 Race
Street, Philadelphia, PA 19103. Copies may be inspected at U.S. EPA,
OAR, 401 M St., SW., Washington, DC 20460, or at the National Archives
and Records Administration (NARA). For information on the availability
of this material at NARA, call 202-741-6030, or go to: http://
www.archives.gov/federal--register/code--of--federal--regulations/ibr--
locations.html.
(ii) Specific gravity (based on fuel composition per ASTM D 1945).
(iii) Carbon weight fraction based on the carbon contained only in
the HC constituents of the fuel=weight of carbon in HC constituents
divided by the total weight of fuel.
(iv) Carbon weight fraction of fuel=total weight of carbon in the
fuel (i.e., includes carbon contained in HC and in CO2)
divided by total weight of fuel.
(d) Calculate the city fuel economy and highway fuel economy from
the grams/mile values for total HC, CO, CO2 and, where applicable, CH3,
OH, HCHO, NMHC and CH4 and, the test fuel's specific gravity, carbon
weight fraction, net heating value, and additionally for natural gas,
the test fuel's composition. 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 40 CFR 86.084-
26(a)(6)(iii) or 40 CFR 86.1837-01 as applicable. The CO2 values
(obtained per paragraph (a) or (b) of this section, as
[[Page 902]]
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
value (obtained per paragraph (c) of this section) shall be recorded to
the nearest whole Btu/lb.
(e)(1) For gasoline-fueled automobiles, the fuel economy in miles
per gallon is to be calculated using the following equation:
mpg=(5174x10\4\xCWFxSG) / [((CWFxHC) + (0.429x CO) +
(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.
(2) Round the calculated result to the nearest 0.1 miles per gallon.
(f)(1) For diesel-fueled automobiles, calculate the fuel economy in
miles per gallon of diesel fuel by dividing 2778 by the sum of three
terms:
(i) 0.866 multiplied by HC (in grams/miles as obtained in paragraph
(d) of this section);
(ii) 0.429 multiplied by CO (in grams/mile as obtained in paragraph
(d) of this section); and
(iii) 0.273 multiplied by CO2 (in grams/mile as obtained
in paragraph (d) of this section).
(2) Round the quotient to the nearest 0.1 mile per gallon.
(g) For methanol-fueled automobiles and automobiles designed to
operate on mixtures of gasoline and methanol, the fuel economy in miles
per gallon is to be calculated using the following equation:
mpg=(CWFxSGx3781.8) / ((CWFexHCxHC) + (0.429xCO) +
(0.273xCO2) + (0.375xCH3 OH) + (0.400xHCHO))
Where:
CWF=Carbon weight fraction of the fuel as determined in paragraph
(c)(2)(ii) of this section.
SG=Specific gravity of the fuel as determined in paragraph (c)(2)(i) of
this section.
CWFexHC=Carbon weight fraction of exhaust hydrocarbons=
CWFg as determined in (c)(2)(ii) of this section (for M100
fuel, CWFexHC=0.866).
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.
CH3 OH=Grams/mile CH3 OH (methanol) as obtained in
paragraph (d) of this section.
HCHO=Grams/mile HCHO (formaldehyde) as obtained in paragraph (d) of this
section.
(h) For automobiles fueled with natural gas, the fuel economy in
miles per gallon of natural gas is to be calculated using the following
equation:
[GRAPHIC] [TIFF OMITTED] TR21SE94.006
Where:
mpge=miles per equivalent gallon of natural gas.
CWFHC/NG=carbon weight fraction based on the hydrocarbon
constituents in the natural gas fuel as obtained in paragraph (d) of
this section.
DNG=density of the natural gas fuel [grams/ft\3\ at 68 [deg]F
(20 [deg]C) and 760 mm Hg (101.3 kPa)] pressure as obtained in paragraph
(d) of this section.
CH4, NMHC, CO, and CO2=weighted mass exhaust
emissions [grams/mile] for methane, non-methane HC, carbon monoxide, and
carbon dioxide as calculated in Sec. 600.113.
CWFNMHC=carbon weight fraction of the non-methane HC
constituents in the fuel as determined from the speciated fuel
composition per paragraph (c)(2) of this section.
CO2NG=grams of carbon dioxide in the natural gas fuel
consumed per mile of travel.
CO2NG=FCNG DNG WFCO2
where:
[[Page 903]]
[GRAPHIC] [TIFF OMITTED] TR21SE94.007
where:
CWFNG=the carbon weight fraction of the natural gas fuel as
calculated in paragraph (d) of this section.
WFCO2=weight fraction carbon dioxide of the natural gas fuel
calculated using the mole fractions and molecular weights of the natural
gas fuel constituents per ASTM D 1945.
[59 FR 39654, Aug. 3, 1994; 59 FR 44795, Aug. 30, 1994, as amended at 59
FR 48537, Sept. 21, 1994; 64 FR 23975, May 4, 1999; 69 FR 18803, Apr. 9,
2004]