EPAct/V2/E-89: Assessing the Effect 

of Five Gasoline Properties on Exhaust 

Emissions from Light-Duty Vehicles 

Certified to Tier 2 Standards

Final Report on Program Design and 

Data Collection
NOTICE

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.

Assessment and Standards Division

Office of Transportation and Air Quality

U.S. Environmental Protection Agency

and

National Renewable Energy Laboratory

U.S. Department of Energy

and

Coordinating Research Council

EPAct/V2/E-89: Assessing the Effect 

of Five Gasoline Properties on Exhaust 

Emissions from Light-Duty Vehicles 

Certified to Tier 2 Standards

Final Report on Program Design and 

Data Collection

EPA-420-R-13-004

April 2013
3 

CONTENTS

I. Executive Summary .................................................................................................5 

II. Introduction ..............................................................................................................6 

III. Test Fuel Specification and Blending ......................................................................8 

IV. Test Vehicle Fleet Sizing and Selection ................................................................40 

V. Test Procedures, Data Collection, Issues Encountered ..........................................49 

VI. Data Reporting .......................................................................................................73 

VII. Summary and Closing Remarks.............................................................................76 

APPENDICES

A. Re-Design of Fuel Matrices for EPAct Program

B. SwRI EPAct/V2/E-89 Fuel Blending Report 

C. Fuel Round Robin Procedure for Sample Handling 

D. Identification of Extreme Values for Round Robin Laboratory Tests 

E. Spreadsheets of Detailed Round Robin Fuel Inspection Data

F. Summary of Oil Sampling Dates and Mileages

G. Fuel Sampling Procedure for Carryover Experiments 

H. Fuel Blending Experiment to Characterize Carryover Effects

I. Additional Fuel Carryover Experiments 

J. Refueling Location Experiments

K. Detailed Measurement and Analysis Methods 

L. LOD/LOQ Method

M. Details of Ford Explorer Oil Level Incident 

N. EPAct NMOG Calculation Protocol 

O. Text of SwRI Phase 3 Testing Report 

P. Derivation of FID Response Factors for Oxygenated Species 
4 

Abbreviations Used in this Report 

API American Petroleum Institute

CARB California Air Resources Board (also ARB) 

CFR Code of federal regulations 

CH4 Methane

CO Carbon monoxide 

CO2 Carbon dioxide 

CRC Coordinating Research Council

EPA US Environmental Protection Agency 

DOE US Department of Energy

DNPH Dinitrophenylhydrazine 

DVPE Dry vapor pressure equivalent (equivalent to RVP) 

E0 Gasoline containing no ethanol 

E10 Gasoline blend containing 10 vol% ethanol 

FBP Final boiling point 

FID Flame ionization detector

FTP Federal test procedure 

HPLC High performance liquid chromatograph 

MON Motor octane number 

MSAT Mobile Source Air Toxics 

NMHC Non-methane hydrocarbons 

NMOG Non-methane organic gases

NOx Nitrogen oxides

NREL National Renewable Energy Laboratory

OBD Onboard diagnostics 

(R+M)/2 Average of RON and MON 

RON Research octane number

RVP Reid vapor pressure 

SwRI Southwest Research Institute 

T50 Temperature at which 50 vol% of a fuel has been evaporated (°F)

T90 Temperature at which 90 vol% of a fuel has been evaporated (°F)

THC Total hydrocarbons 

 
5 

I. EXECUTIVE SUMMARY

 This report describes program design and data collection in the EPAct/V2/E-89 light duty 

gasoline vehicle fuel effects study, which examined the exhaust emission impacts of changes in 

five fuel properties (ethanol, T50, T90, aromatics, and RVP (specified as DVPE)) over a range 

covering current market fuels and potential mid-level ethanol blends. Testing was performed by 

Southwest Research Institute, and program sponsors were the U.S. Environmental Protection 

Agency, U.S. Department of Energy via the National Renewable Energy Laboratory, the 

Coordinating Research Council, and the Lubrizol Corporation. 

 The fuel matrix consisted of 27 fuels arranged according to a partial factorial design 

optimized for selected interactions of interest, plus an E85 fuel tested on a subset of vehicles. 

The test vehicle fleet consisted of 15 new light duty cars and trucks of 2008 model year selected 

from among high sales makes and models to provide a representative sample of the fleet of 

properly-operating vehicles meeting the U.S. Federal Tier 2 emission standards.

1

 Given the 

relatively low level of emissions from these vehicles, a number of design and procedural steps 

were undertaken to minimize the impacts of measurement variability and other artifacts on data 

quality. 

 Data collected included typical regulated pollutants by bag and second-by-second plus 

speciated emissions for a subset of tests and bags. Data for 16 relevant onboard diagnostic 

parameters were also captured for each test on a second-by-second basis. Complete data were 

generated for 926 tests, with 30 additional tests containing valid measurements for regulated 

emissions.2

 Sponsors agreed that analysis of the resulting dataset would be performed and 

published independently. 

 

 

1 An additional (16th) vehicle performed testing on the E85 fuel. 2 Program data is available via the EPA OTAQ website at http://www.epa.gov/otaq/fuelsmodel.htm
6 

II. INTRODUCTION

 Prior fuel effects models, such as the EPA Predictive Model and Complex Model,3 were 

based on data taken on 1990s-technology vehicles meeting the Tier 0 and Tier 1 emission 

standards, levels an order of magnitude higher than current (Tier 2-compliant) vehicles. With the 

fleet turning over to much lower-emitting vehicles, the Agency and stakeholders were interested 

in generating a coherent body of updated fuel effects data on which policy could be based going 

forward. Recognizing this issue, Congress, in Section 1506 of the Energy Policy Act of 2005, 

directed EPA to produce an updated fuel effects model representing the gasoline vehicle fleet at 

the time of the study. Carrying out other statutory requirements, such as an anti-backsliding 

assessment of the effects of increased renewable fuels use on air quality as outlined in Section 

209 of the Energy Independence and Security Act of 2007, were also dependent upon updated 

fuel effects data. 

In September 2007, Southwest Research Institute (SwRI) began conducting work in San 

Antonio, Texas, on a series of tasks and assignments for EPA related to the statutory 

requirement. By January 2009, SwRI had completed Phases 1 and 2 the EPAct program. These 

pilot phases, described in a separate document, involved testing of 19 light duty cars and trucks 

(subsequently referred to as the “EPAct fleet”) on three fuels, at two temperatures.4

 In March 2009, SwRI began work on Phase 3 (the main program), which was jointly 

supported by EPA, the U.S. Department of Energy (DOE) through the National Renewable 

Energy Laboratory (NREL), and the Coordinating Research Council (CRC). In addition, 

Lubrizol Corporation provided material and analytical support. This report covers work 

conducted for Phase 3, also known as EPAct/V2/E-89, which involved the testing of fifteen of 

the high-sales Tier 2 compliant vehicles from the EPAct Phase 1 fleet using twenty-seven test 

fuels covering typical ranges of five fuel parameters. Phase 3 also included testing of the four 

 

3 See “Technical Support Document: Analysis of California’s Request for Waiver of the Reformulated Gasoline 

Oxygen Content Requirement for California Covered Areas”, document number EPA420-R-01-016. See also 40 

CFR 80.45.

4 EPAct program Phases 1-2 are described in a memorandum to the Tier 3 docket EPA-HQ-OAR-2011-0135. 
7 

flexible-fuel vehicles (FFVs) from the EPAct fleet on an E85 fuel (three of these vehicles were 

among the 15-vehicle test fleet). Phase 3 data collection was completed in June 2010. 
8 

III. TEST FUEL SPECIFICATION AND BLENDING

 A. Design of Fuel Matrix 

 1. Selection of Fuel Parameters for Investigation

 Gasoline is a mixture of hundreds of hydrocarbon species, with boiling points spanning 

the range of 100-400°F, and molecular size ranging from four to ten carbons. Depending on the 

source of the parent crude oil and configuration of the refinery producing the gasoline, the 

proportions of particular chemical species can vary widely. This is acceptable so long as a 

number of key bulk properties of the mixture remain within a range that ensures acceptable 

operation of vehicles and other equipment designed to use it. Over the past few decades, EPA 

and other agencies have also found it useful to regulate some of these properties to control 

harmful emissions.

 While an exhaustive study of effects of gasoline properties on emissions could include 

dozens of parameters, producing results with an acceptable level of statistical power would 

require such a large and complex design that it would be impractically lengthy and expensive. 

To narrow the scope a survey was made of available data for recent technology vehicles, with 

special attention paid to the expected magnitude of emission changes caused by fuel properties,

as well as how important characterization of an effect might be in a regulatory context. 

Databases used for estimating the magnitude of emission impacts included those associated with 

the EPA Complex and Predictive models, the California Air Resources Board Predictive Model, 

the CRC E-67 and E-74b test programs, as well as the 2005-6 MSAT test program conducted by 

EPA and several automakers. Table III-1 lists the parameters initially considered as candidates 

for study and summarizes selection criteria related to each.
9 

Table III-1. Fuel parameters considered for inclusion in the study. 

Fuel Parameter

Data Availability for 

Latest Technology 

Vehicles

Expected Magnitude 

of Emission Impact Fuel Policy Relevance

Aromatics Little High High

Ethanol Some Uncertain High

RVP Some Uncertain High

T50 Little Uncertain Low

T90 Little Uncertain Low

Sulfur Some High High

Olefins Little Uncertain Uncertain

Octane number Little Low Low

Drivability index Little Low Low

Total oxygen Little Uncertain Low

Polyaromatics Little Uncertain Uncertain

 Initial assessment of costs and program duration suggested it would not be feasible to 

include more than five fuel parameters and their interactions. Based on a combination of the 

criteria shown, the five parameters listed at the top of this table were chosen as the study targets. 

Two other parameters, sulfur and olefin content, were also of interest; examination of sulfur 

would require a different program design due to involvement of the exhaust catalyst, and olefins 

were deferred for study later.

5,6

 2. Selection of Fuel Parameter Ranges and Levels

 Fuel parameters may have linear or nonlinear impacts on emissions. To capture a 

nonlinear impact, three or more treatment levels of a given parameter must be included in the 

study design. Statistical models of data from prior studies suggested that T50, T90, and ethanol 

content may have nonlinear impacts on emissions. Based on this information, EPA originally 

planned to test three levels of ethanol spanning the range of E0-E10 (the limit for legal market 

fuels at that time). During the design process, DOE (via NREL) offered additional funding to 

add E15 and E20 fuels to broaden the database to include fuel blends that might be expected 

 

5 A subsequent study on the effects of olefins using the same 15-vehicle test fleet as this study was published as 

Maryam Hajbabaei, Georgios Karavalakis, J. Wayne Miller, Mark Villela, Karen Huaying Xu, Thomas D. Durbin, 

Impact of olefin content on criteria and toxic emissions from modern gasoline vehicles, Fuel, Volume 107, May 

2013, Pages 671-679, ISSN 0016-2361, 10.1016/j.fuel.2012.12.031. 6 A subsequent study on the effects of sulfur content using the same makes and models as this study was published 

by EPA as document EPA-420-D-13-003, “The Effects of Gasoline Sulfur Level on Emissions from Tier 2 Vehicles 

in the In-Use Fleet”. 
10 

appear in the market in the future. After this adjustment, four levels of ethanol were selected at 

0%, 10%, 15%, and 20% by volume. Five levels of T50 were chosen to allow detailed 

characterization of any interaction with ethanol. Finally, to examine potential nonlinear impacts 

of T90, two fuels were added with an intermediate level of this parameter.. 7

 The remaining two 

parameters, aromatic content and RVP (reported in this program as DVPE), had two levels. 

 The parameter ranges to be covered for T50, T90, aromatic content, and RVP were

selected to represent the range of in-use fuels based on a review of the Alliance of Automobile 

Manufacturers’ 2006 North American Fuel Survey. As the emissions tests were to be performed 

at the nominal temperature of 75°F, summer survey data was used. Since the effect of fuel 

changes on emissions was expected to be small in comparison to other sources of test-to-test 

variability, the span of fuel parameter ranges was maximized in order to increase the likelihood 

of discerning statistically significant results. Test fuel parameter ranges were originally drafted 

to span roughly the 5th to 95th percentiles of survey results for in U.S. gasoline, though some test 

fuel parameters were adjusted after the actual blending process began (discussed further in 

section III.B). An intermediate level of T50 in E0 fuels was selected to coincide with the high 

level of T50 in E10 fuels. Similarly, an intermediate level of T50 in E10 fuels was selected to 

coincide with the low level of T50 in E0 fuels. 

 For E15 and E20 fuels, the T90, aromatic content, and DVPE ranges selected for E0 and 

E10 fuels were applied. A single level of T50 was selected for E20 blends based on the 

information obtained from CRC report No. 648 (2006 CRC Hot-Fuel-Handling Program) as well 

as petroleum industry sources which indicated that it was largely independent of the hydrocarbon 

fraction of the fuel and would not deviate more than several degrees from 160°F due to the 

presence of a large fraction of ethanol.

8

 At the time this fuel matrix was being designed, no 

information was available on distillation properties of E15 fuels. Two levels of T50 were 

 

7 The intermediate level of T90 occurs along one edge of the fuel domain in Phase 3. Statistical analysis of any 

nonlinear T90 effect was intended to rely on a fuel used in Phase 1 of the program as an additional source of data for 

the intermediate T90 level.

8 As ethanol blend level moves beyond 10 vol%, T50 becomes increasingly correlated (inversely) with ethanol 

content. At E15, the two can be manipulated independently with some effort within a relatively limited range. By 

E20, the behavior of the center of the distillation curve (where T50 lies) is dominated by ethanol’s boiling point, and 

thus T50 cannot be moved outside a narrow range around 165°F. Thus, T50 and ethanol should only be understood 

to be independently blended parameters at E10 and below. 
11 

selected for the E15 fuels, the low level equal to the lowest T50 assumed for E10 fuels and the 

high level being a linear interpolation between the highest T50 of E10 fuels and the sole T50 

level of E20 fuels. Table III-2 shows the levels and range of parameters chosen during the initial 

design of the Phase 3 fuel set. Some of these parameters were adjusted during subsequent 

blending steps (discussed further in section III.B). 

Table III-2. Summary of initial Phase 3 test fuel set design. 

Fuel Parameter Number of Levels Values to Be Tested

Ethanol (vol%) 4 0, 10, 15, 20

T50 (°F) 5 150, 160 (E20 only), 190, 220, 240

T90 (°F) 3 300, 325, 340

Aromatics (vol%) 2 15, 40

RVP (psi) 2 7, 10

 3. Statistical Design of the Fuel Matrix

 Studies involving multiple levels of multiple variables are ideally conducted in such a 

way that each parameter is varied independently through all its levels while the others are held 

constant, thus generating data from all possible combinations of treatment levels (referred to as a 

factorial design). Given the levels of treatments outlined above, the Phase 3 fuel set would 

require some 240 fuels to be blended and tested to examine each point of a factorial matrix. This 

clearly being impractical, use of a partial factorial design was utilized. This arrangement uses a 

subset of all the possible fuel blends to allow characterization with statistical confidence of the 

main effects (i.e., the fuel parameters themselves) plus a pre-selected subset of interactions 

between the main effects.9

 Interactions of interest were chosen based on models from prior 

studies as well as engineering judgment, and are as follows: ethanol interactions with each of the 

other fuel parameters, plus T50-squared and ethanol-squared. With the five main effects plus 

these six interactions, the design was to be optimized for 11 potential model terms. 

 

9 What is sacrificed in a partial factorial design is the ability to properly characterize all interactions between the 

study parameters. Interactive effects beyond those for which the design is optimized are confounded with others to 

varying degrees, and thus conclusions about them can’t generally be made with statistical confidence.
12 

 Selection of the best subset of fuels for a partial factorial design is a computationally 

intensive process, for which specialized software has been developed. This work was done by

SwRI statisticians Robert Mason and Janet Buckingham. A matrix of 27 fuels as shown in Table 

III-3 was eventually constructed to maximize statistical performance over the desired range of 

parameters. The statisticians’ report describing the matrix development process is available as 

Appendix A.10 

 

 

10 The statisticians’ report covers matrix design through several stages of evolution of program objectives and 

funding levels. The fuel matrix shown in Table 9 of the report was eventually used for Phase 3, with the exception 

of fuels 17-19, which were tested in earlier phases of the program. The Phase 3 matrix of 27 fuels was intended to 

stand on its own for modeling purposes, with optional inclusion of fuels 17-19 in the database as “centered” fuels. 

The development of fuels 17-19 is described in the SwRI EPAct/V2/E-89 Fuel Blending Final Report attached as 

Appendix B.
13 

Table III-3. Phase 3 fuel matrix resulting from partial factorial design. 

Test Fuel 

Numbera

T50, o

F

T90, o

F

Ethanol, 

vol.%

DVPE, 

psi

Aromatics, 

vol.%

1 150 300 10 10 15

2 240 340 0 10 15

3 220 300 10 7 15

4 220 340 10 10 15

5 240 300 0 7 40

6 190 340 10 7 15

7 190 300 0 7 15

8 220 300 0 10 15

9 190 340 0 10 40

10 220 340 10 7 40

11 190 300 10 10 40

12 150 340 10 10 40

13 220 340 0 7 40

14 190 340 0 7 15

15 190 300 0 10 40

16 220 300 10 7 40

20 160 300 20 7 15

21 160 300 20 7 40

22 160 300 20 10 15

23 160 340 20 7 15

24 160 340 20 10 15

25 160 340 20 10 40

26 150 340 15 10 40

27 190 340 15 7 15

28 190 300 15 7 40

30 150 325 10 10 40

31 160 325 20 7 40 a Fuels 17-19 were tested in an earlier phase of the program. Fuel 29 is an E85 fuel

not included in the statistical matrix design.

 4. Test Fuel Specification

 In addition to the five fuel properties that were the focus of this program, the test fuel 

specifications included a number of parameters which were known or suspected to affect 

emissions. In an attempt to produce as controlled an experiment as possible, the levels of those 

parameters were specified within certain bounds across all test fuels. Examples of these 

properties include olefin and sulfur content and octane number. An olefin specification of 7.0 ± 

1.5 vol% was used, based on the U.S. average computed from the Alliance of Automobile 
14 

Manufacturers’ 2006 Summer North American Fuel Survey. Because of its important impact on 

benzene emission performance, the fuel benzene content specification was set at 0.62 ± 0.15 

vol%, the level of the refinery average gasoline benzene standard effective on January 1, 2011. 

The sulfur content specification of 25 ± 5 mg/kg (ppmw) was selected to ensure that the level

remained within a reasonably narrow range capped by the current refinery/importer annual 

average standard of 30 mg/kg. The minimum (R+M)/2 octane specification of 87 was based on 

minimum requirements of test vehicles selected for this program. Blending tolerances for all 

properties are shown in Table III-4. Note that there was no upper limit on octane number, so its 

value tends to be correlated with ethanol content since ethanol has a high octane number and its 

level varied widely across the blends.

 Special attention was paid to the distribution of aromatic molecule sizes because of 

potential impacts on particulate matter emissions. An attempt was made to maintain consistent 

proportions of aromatic-containing molecules with seven or more carbon atoms. The ratios of 

2:2:2:1 were chosen for C7:C8:C9:C10 aromatics based on detailed hydrocarbon analysis data for 

commercial gasolines that was available to EPA at the time of fuel blending. As a practical 

matter of meeting the distillation targets, the proportions had to be adjusted to include more C7

and C8 aromatics for fuels with a combination of low T90 and high aromatics. 

 The fuel specification also included T10, FBP, oxidation stability, copper strip corrosion 

and solvent-washed gum content requirements taken from the ASTM D4814 Standard 

Specification for Automotive Spark-Ignition Engine Fuel. Furthermore, a limit on total content 

of oxygenates other than ethanol was adopted to safeguard the test fuels against such 

contamination. Finally, a number of uncontrolled fuel properties used in emissions test 

calculations were appended to the fuel specification table to make sure they were measured prior 

to the launch of the emissions test program and in the EPAct/V2/E-89 Fuels Round Robin to be 

conducted. They included carbon, hydrogen and oxygen content, density, and heat of 

combustion. 

 A single E85 fuel (fuel number 29) was also incorporated in this program for testing in 

flexible fuel vehicles. This fuel was not blended along with other fuels used in Phase 3 of the 
15 

EPAct/V2/E-89 Program, but was obtained from CRC. Its properties are provided in Section 

III.D.

 

 B. Test Fuel Development and Blending 

 1. Development and Verification of Test Fuel Formulations 

All fuels tested in Phase 3 of the EPAct/V2/E-89 Program were formulated by EPA in 

conjunction with Haltermann Solutions, Houston, Texas (with the exception of fuel 29, the E85 

blend). To facilitate the formulation process, Haltermann made a detailed set of property data 

for their gasoline blending components available to EPA for use in designing fuels for this 

program. (These data were deemed confidential business information and are not provided in 

this report.) The majority of these components were blendstock streams taken from various 

points in refinery operations (e.g., reformate, alkylate, isomerate, light naphtha, etc.), ensuring 

that the resulting test fuels contained the typical range of components found in actual market 

fuels. 

In the development of each test fuel formulation, EPA used a computational blending 

model to define and adjust the blend recipe from the available components while Haltermann 

prepared and characterized lab-scale hand blends. Distillation by ASTM D86 method, aromatics 

and olefins by D1319, DVPE by D5191 and ethanol content by D5599 were always measured at 

this stage. Sulfur by D5453 was measured if its predicted level was ≥ 27 mg/kg, benzene by 

D3603 when its predicted content was ≥0.70 vol% and octane numbers by D2699 and D2700 if 

predicted knock index (RON+MON)/2 was ≤88.0. The use of distillation stills equipped with 

OptiDist or equivalent technology was required for all E10, E15, and E20 fuels.11

The distillation parameters, DVPE, as well as the aromatic and olefinic content of hand 

blends were measured by Haltermann and verified by a third-party laboratory of Haltermann’s 

 

11 Accurately measuring T50 becomes increasingly difficult as more ethanol is blended into the fuel. Older still 

models were found to generate results with unacceptable levels of variability. OptiDist is a trade name denoting 

enhanced automated control of distillation parameters that produces better results than traditional methods.
16 

choice (typically Core Laboratories, Dixie Services, BSI-Inspectorate, or Saybolt). Single 

measurements were allowed for benzene, sulfur, and ethanol content, as well as MON and RON, 

though confirmation could be performed at one of the third-party laboratories at Haltermann’s 

discretion. 

As the development of fuel formulations progressed, it became clear that some property 

values in the initial fuel matrix design (Table III-3) could not be met within acceptable 

tolerances. They included: 

• T50 target of 150±4°F for the E15 fuel 26 

• T50 target of 160±4°F for all E20 fuels 

• DVPE target of 6.65±0.15 psi for the vast majority of “low” DVPE fuels 

• RON target of 93±2 for many fuels

• MON target of 85±2 for many fuels

• (RON + MON)/2 target of 87±2 for many fuels

The initial blending experiments also revealed that the upper T50 limit for E15 fuels was 

as high as 220°F, considerably higher than the 190°F target assumed for fuels 27 and 28 in the 

absence of relevant information in the technical literature. 

Finally, a decision was made to replace the aromatic content level of 40 vol% with a 

target of 35 vol% to facilitate blending of “high” aromatic content fuels. It was also thought that 

the lower target would be more representative of future market fuels. 

As a consequence of the observations and decisions mentioned above, the following 

modifications were incorporated in the fuel specification: 

• T50 target of 160±4°F for the E15 fuel 26 

• T50 target of 220±4°F for the E15 fuels 27 and 28 

• T50 target of 165±4°F for all E20 fuels

• DVPE range of 7±0.25 psi for the “low” DVPE fuels 
17 

• Aromatic content target of 35±1.5 vol% for all “high” aromatic content fuels 

• Separate RON and MON targets were eliminated, replaced by (RON + MON)/2 

target of ≥87 for all fuels

These specification changes are reflected in Table III-4, and the resulting domain of 

ethanol content vs. T50 of the test fuel matrix is shown in Figure III-1. 
18 

Table III-4. Final test fuel specification for blending. 

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Density, 60oF - D4052 NA Report Report Report Report Report Report Report Report Report Report Report Report Report Report

API Gravity, 60o

F oAPI D4052 NA Report Report Report Report Report Report Report Report Report Report Report Report Report Report

Ethanol Content vol. % D5599

E0: < 0.1; 

E10: ± 0.5; 

E15: ± 0.5; 

E20: ±0.5; 

E85: ±2

10 0 10 10 0 10 0 0 0 10 10 10 0 0

Total Content of Oxygenates Other 

Than Ethanol vol. % D5599 - <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1 <0.1

T10 oF D86 - <158 <158 <158 <158 <158 <158 <158 <158 <158 <158 <158 <158 <158 <158

T50 oF D86 ± 4 150 240 220 220 240 190 190 220 190 220 190 150 220 190

T90 oF D86 ± 5 300 340 300 340 300 340 300 300 340 340 300 340 340 340

FBP oF D86 - <437 <437 <437 <437 <437 <437 <437 <437 <437 <437 <437 <437 <437 <437

DVPE psi D5191 ± 0.25 10 10 7 10 7 7 7 10 10 7 10 10 7 7

Aromatics vol. % D1319 ± 1.5 15 15 15 15 35 15 15 15 35 35 35 35 35 15

Olefins vol. % D1319 ± 1.5 7 7 7 7 7 7 7 7 7 7 7 7 7 7

Benzene vol. % D3606 ± 0.15 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62

S mg/kg D5453 ± 5 25 25 25 25 25 25 25 25 25 25 25 25 25 25

(RON + MON)/2 - Calc. - > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0

C mass % D5291 mod* - Report Report Report Report Report Report Report Report Report Report Report Report Report Report

H mass % D5291 mod* - Report Report Report Report Report Report Report Report Report Report Report Report Report Report

O mass % D5599 - Report Report Report Report Report Report Report Report Report Report Report Report Report Report

Water Content mg/kg E1064 - Report Report Report Report Report Report Report Report Report Report Report Report Report Report

Net Heat of Combustion MJ/kg D4809 - Report Report Report Report Report Report Report Report Report Report Report Report Report Report

Oxidation Stability minute D525 - >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240

Copper Strip Corrosion, 3h at 122oF - D130 - <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1

Solvent-Washed Gum Content mg/100 ml D381 - < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5

* Method adapted to gasoline by the testing laboratory

TEST FUELS

PROPERTY UNIT METHOD BLENDING 

TOLERANCE
19 

Table III-4 Cont. Final test fuel specification for blending. 

15 16 20 21 22 23 24 25 26 27 28 30 31

Density, 60oF - D4052 NA Report Report Report Report Report Report Report Report Report Report Report Report Report

API Gravity, 60o

F o

API D4052 NA Report Report Report Report Report Report Report Report Report Report Report Report Report

Ethanol Content vol. % D5599

E0: < 0.1; 

E10: ± 0.5; 

E15: ± 0.5; 

E20: ±0.5; 

E85: ±2

0 10 20 20 20 20 20 20 15 15 15 10 20

Total Content of Oxygenates Other 

Than Ethanol vol. % D5599 - <0.1 <0.1 <0.2 <0.2 <0.2 <0.2 <0.2 <0.2 <0.15 <0.15 <0.15 <0.1 <0.2

T10 oF D86 - <158 <158 <158 <158 <158 <158 <158 <158 <158 <158 <158 <158 <158

T50 oF D86 ± 4 190 220 165 165 165 165 165 165 160 220 220 150 165

T90 oF D86 ± 5 300 300 300 300 300 340 340 340 340 340 300 325 325

FBP oF D86 - <437 <437 <437 <437 <437 <437 <437 <437 <437 <437 <437 <437 <437

DVPE psi D5191 ± 0.25 10 7 7 7 10 7 10 10 10 7 7 10 7

Aromatics vol. % D1319 ± 1.5 35 35 15 35 15 15 15 35 35 15 35 35 35

Olefins vol. % D1319 ± 1.5 7 7 7 7 7 7 7 7 7 7 7 7 7

Benzene vol. % D3606 ± 0.15 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62 0.62

S mg/kg D5453 ± 5 25 25 25 25 25 25 25 25 25 25 25 25 25

(RON + MON)/2 - Calc. - > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0 > 87.0

C mass % D5291 mod* - Report Report Report Report Report Report Report Report Report Report Report Report Report

H mass % D5291 mod* - Report Report Report Report Report Report Report Report Report Report Report Report Report

O mass % D5599 - Report Report Report Report Report Report Report Report Report Report Report Report Report

Water Content mg/kg E1064 - Report Report Report Report Report Report Report Report Report Report Report Report Report

Net Heat of Combustion MJ/kg D4809 - Report Report Report Report Report Report Report Report Report Report Report Report Report

Oxidation Stability minute D525 - >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240

Copper Strip Corrosion, 3h at 122o

F - D130 - <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1 <No. 1

Solvent-Washed Gum Content mg/100 ml D381 - < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5 < 5

* Method adapted to gasoline by the testing laboratory

UNIT METHOD BLENDING 

TOLERANCE

TEST FUELS

PROPERTY
20 

Figure III-1. Nominal ethanol content vs. T50 domain of E0-E20 fuels (Final version) 

Overall, 21 different blending components were used in this program, between 9 and 16 

per fuel. The process of developing formulations for each test fuel required as many as seven 

lab-scale iterations in some cases with particularly challenging combinations of fuel parameters.

 Once the T10, T50, T90, FBP, DVPE, knock index as well as the aromatic, olefinic, 

benzene, sulfur and ethanol content requirements of the specification shown in Table III-4 were 

met, the remaining parameters listed in that specification were measured. If they also met the 

requirements listed in Table III-4, the final specification for the bulk blend of the fuel was issued 

by EPA and NREL using the template shown in Table III-4. In each such bulk blend 

specification, the approved hand blend results were used as targets for the distillation parameters, 

DVPE as well as the aromatic and olefinic content. The specification shown in Table III-4 

150 160 170 180 190 200 210 220 230 240 250

T50, o

F

0

5

10

15

20

Etha nol Conte nt, vol. %
21 

included T30 and T70 to make sure that the distillation curves of the hand blends were closely 

reproduced in the bulk blends. This specification and the corresponding fuel formulation (blend 

recipe) were subsequently provided to Haltermann for use in the preparation of the bulk blends. 

The use of hand blending results as targets for the bulk blends was done to accommodate 

setting of realistic targets and tolerances for the fuel blending subcontractor to follow. As shown 

in Section III.D, this approach still kept the parameters in question within tight blending 

tolerance limits.
22 

Table III-5. Bulk blend specification template. 

PROPERTY UNIT METHOD BLENDING 

TOLERANCE SPECIFICATION

Density, 60oF - D4052 - Report

API Gravity, 60oF oAPI D4052 - Report

Ethanol Content vol. % D5599 

E0: <0.1

E10: ±0.5 

E15: ±0.5 

E20: ±0.5 

Per Table III-4 

Total Content of Oxygenates 

Other Than Ethanol vol. % D5599 - <0.1 

Distillation 

T10

o

F D86 ±5 Value based on 

hand blend data

T30

o

F D86 ±5 Value based on 

hand blend data

T50

o

F D86 ±4 Value based on 

hand blend data

T70

o

F D86 ±5 Value based on 

hand blend data

T90

o

F D86 ±5 Value based on 

hand blend data

FBP oF D86 - <437

DVPE psi D5191 ±0.15 Value based on 

hand blend data 

Aromatics vol. % D1319 ±1.5 Value based on 

hand blend data

Olefins vol. % D1319 ±1.5 Value based on 

hand blend data

Benzene vol. % D3606 ±0.15 0.62

S mg/kg D5453 ±5 25

(RON+MON)/2 - Calc. - ≥87.0

C mass % D5291 mod* - Report

H mass % D5291 mod* - Report

O mass % D5599 - Report

Water Content mg/kg E1064 - Report

Net Heat of Combustion MJ/kg D4809 - Report

Oxidation Stability minute D525 - >240

Copper Strip Corrosion, 3h at 

122oF - D130 - <No. 1 

Solvent-Washed Gum Content mg/100 

ml D381 - <5

*Method adapted by a specific laboratory to testing of gasolines 
23 

 2. Bulk Blending and Analysis of Test Fuels

 Haltermann prepared the bulk blends and adjusted their properties until they met the bulk 

blend specifications. Distillation parameters, DVPE, MON, RON as well as the aromatic, 

olefinic, benzene and S content were measured during bulk blending by Haltermann and verified 

by another laboratory, usually Core Laboratories, Dixie Services, BSI-Inspectorate, or Saybolt. 

Single measurements were required for the remaining parameters listed in Table III-5 and could 

also be performed at one of the mentioned laboratories at Haltermann’s discretion.

Once the bulk blend specification was met, a sample of the fuel was shipped to SwRI for 

confirmatory testing. If SwRI analytical results fell inside the test method reproducibility limits 

for all parameters listed in Table III-5, EPA and NREL approved the bulk blend for shipment to 

SwRI. If they fell outside the method reproducibility limits, further tests and/or blend 

adjustments followed until the requirements of the specification were met. 

 C. Shipping, Storage and Handling of Test Fuels

For contingency purposes the procured quantities of test fuels (500 gallons each)

exceeded the anticipated needs to complete the program by 20%. The fuels were shipped by 

Haltermann to SwRI in epoxy-lined, 55-gallon drums and stored on site in a temperaturecontrolled facility (Figure III-2). The storage temperature for unopened drums was 70°F ± 5°F. 

Any drums that were to be opened (for vehicle fueling or sampling) were cooled down to a 

temperature of <50°F at a dedicated cold storage facility located behind the emissions laboratory 

next to the vehicle refueling bay. The temperature of both fuel storage facilities was 

continuously recorded, and was verified at least once a day. 

 Upon arrival at SwRI, all fuels received independent identifiers which included the 

EPAct/V2/E-89 fuel number, a SwRI fuel code, and a project-specific supplementary three-letter 

code (Table III-6). All fuel drums and corresponding work requests included all three 

designators in an effort to assure the correct fuel was being used at any point in the test program. 
24 

Additionally, each individual drum received a sequential number. These unique alphanumeric 

designations assigned to individual drums were recorded and verified by two individuals each 

time a test vehicle was fueled.

Each time a full drum was opened, the properties of its contents were verified using a 

portable PetroSpec gasoline analyzer. Based on these results, no mislabeling of fuel drums 

occurred during this program. 

With the exception of drum content verification using the PetroSpec analyzer, the 200 

gallons of fuel 29 (E85) provided by the CRC were handled in the same manner as the E0-E20 

fuels. 
25 

Table III-6. Test fuel identifiers used by SwRI. 

 

EPAct/V2/E-89 

FUEL NUMBER SwRI FUEL CODE SwRI FUEL NAME

1 EM-6995-F SAT

2 EM-6953-F ELP

3 EM-7053-F FLG

4 EM-6996-F HOU

5 EM-7061-F MCI

6 EM-7092-F IND

7 EM-6954-F JNU

8 EM-6936-F BWI

9 EM-6955-F KAW

10 EM-7093-F LNK

11 EM-7055-F MIA

12 EM-6997-F MLS

13 EM-6965-F CLF

14 EM-6956-F BNA

15 EM-6957-F OAK

16 EM-7056-F OSH

20 EM-7057-F PHX

21 EM-7058-F RNO

22 EM-7001-F SLC

23 EM-7059-F SFO

24 EM-6998-F TEX

25 EM-7073-F TUL

26 EM-7094-F YAK

27 EM-7095-F BOS

28 EM-7096-F NBA

29 EM-6975-F E80

30 EM-7060-F BUF

31 EM-7074-F GPZ
26 

Figure III-2. Constant-temperature storage of unopened fuel drums 

 D. Fuels Round Robin 

The EPAct/V2/E-89 Fuels Round Robin was launched in October 2009 with the support 

of the Coordinating Research Council (CRC). Its objective was to supplement the fuel 

inspection data previously generated for the drum blends by Haltermann, Core Laboratories, 

Dixie Services, BSI-Inspectorate, Saybolt, and SwRI with additional results, especially for the 

parameters most critical to this program, i.e. T50, T90, DVPE, and ethanol and aromatic content. 

The complete lists of parameters which were measured in the 27 E0 through E20 fuels and the 

E85 fuel 29 are provided in Tables III-6 and III-7, respectively.

 Round robin participants included BP, Chevron, ConocoPhillips, EPA, ExxonMobil, 

Marathon, PAC (distillation equipment manufacturer) and Shell. The total number of 

laboratories which measured the properties of fuels used in this program thus increased to 14. 

Tables III-6 and III-7 show the total number of test results which were eventually generated for
27 

each fuel using the specific tests. It is worth noting that at least six T50, T90, DVPE, ethanol 

content and aromatic content results were available for each E0-E20 fuel. 

Table III-7. Parameters measured in E0-E20 fuels in EPAct/V2/E-89 fuels round robin. 

 

 

 Density, 60o

F D4052 4

 API Gravity, 60o

F D4052 4

 Ethanol D5599 6

 Total Content of Oxygenates Other Than Ethanol D5599 2-4

 Distillation D86 6-12

 DVPE (EPA equation) D5191 9-10

 Aromatics D1319 7

 Olefins D1319 7

 Benzene D3606 4-5

 S D5453 6

 RON D2699 4

 MON D2700 4

 C D5291 mod.* 4

 H D5291 mod.* 4

 O D5599 3-6

 Net Heat of Combustion D4809 3

 Water E-1064 1-2

 Lead D3237 0-1

 Copper Strip Corrosion D130 1

 Solvent Washed Gum Content D381 1

 Oxidation Stability D525 1

* Method adapted by individual laboratories to testing of gasolines

PROPERTY TEST METHOD

TOTAL NUMBER 

OF TEST RESULTS 

PER FUEL
28 

Table III-8. Parameters measured in E85 fuel during EPAct/V2/E-89 fuels round robin. 

 

 The instructions issued to the participants at the outset of the round robin included special 

requirements regarding test methods D86, D5501 and D5291. More specifically, they were 

requested to: 

• Use distillation stills equipped with enhanced distillation rate control technology to 

perform D86 distillations on ethanol containing fuels. It turned out that the round robin 

participants who met this requirement all used PAC stills featuring OptiDist technology. 

They were also instructed to perform charge volume scans for improved measurement 

precision. Seven round robin participants complied with this request.

 Density, 60oF D4052 8

 API Gravity, 60o

F D4052 8

 Ethanol D5501 mod.* 5

 Methanol D5501 mod.* 7

 Distillation D86 11

 DVPE (EPA equation) D5191 10

 Benzene D5580 1

 S D5453 3

 C D5291 mod.** 4

 H D5291 mod.** 4

 O D5501 mod.* 5

 Water E203 6

 Net Heat of Combustion D4809 1

 Solvent Washed Gum D381 2

 Unwashed Gum D381 2

 Acidity (as acetic acid) D1613 1

 pHe D6423 2

 Inorganic Chloride D7319 1

 Copper D1688 modified as outlined in D4806 1

* Method adapted by individual laboratories to testing of E85 fuels

** Method adapted by individual laboratories to testing of gasolines

PROPERTY TEST METHOD

TOTAL NUMBER 

OF TEST RESULTS 

PER FUEL
29 

• Generate C and H content data using the D5291 test method modified for use with 

gasoline. The standard version of this method is “not recommended for analysis of 

volatile materials such as gasoline”. However, some contract and petroleum industry 

laboratories are known to have adapted this method to testing of volatile petroleum 

products and that support on this issue was available from test equipment manufacturers. 

Overall, four participants used such a modified D5291 method in this program. 

• Generate ethanol content data for the E85 fuel 29 by means of the D5501 test method 

modified for use with E85 fuels. The standard version of this method is applicable to 

denatured fuel ethanol containing 93-97 mass % of ethanol. In response to this request, 

two of the participating laboratories adapted the ASTM D5501 method to ethanol levels 

typical of E85 fuels. To this end, they utilized draft #4 of the ASTM 5501-09 Proposed 

Revision of Standard Test Method for Determination of Ethanol Content of Mid and 

High Level Ethanol Fuels by Gas Chromatography (valid over the 20-100 mass % range) 

which at the time was being balloted by ASTM Subcommittee D02.04. It was also 

determined that the three laboratories which had previously generated D5501 data on the 

E85 fuel 29 for the CRC also used their own, in-house versions of the D5501 method 

adapted to testing of E85 fuels. 

 

 To ensure consistency with the best industry practice, a Procedure for Sampling and 

Handling of Gasoline Samples was developed with oil company assistance for use in the round 

robin. It was provided to SwRI and is included in this report as Appendix C. 

 Finally, to enable blind testing, a new set of designations was assigned to the test fuels. 

The only fuel which was recognizable to the participants prior to its analysis was the E85 fuel 29 

which was subjected to a different battery of tests than the other 27 fuels. 

 The fuel samples reached round robin participants by mid-October 2009. By mid-March 

2010, all promised data were received by the EPA. Shortly thereafter, a blinded set of round 

robin results was made available to all participants for review, so that each could determine if 

their data were correctly entered into the EPAct/V2/E-89 database. At the same time, the EPA
30 

and NREL performed a preliminary review of the whole data set, identified results which were 

obviously in error and requested retesting by the respective laboratories. 

 Following the approval of round robin database entries by all participants and the 

incorporation of any results of retesting along with fuel property data generated earlier in the 

program, the EPA statistician identified outliers in the data using the methodology described in 

ASTM E178-08 Standard Practice for Dealing with Outlying Observations. The details of this 

methodology as applied to the Phase 3 EPAct/V2/E-89 fuel data set have been summarized by 

the EPA statistician and are included in this report as Appendix D. 

 The final, blinded EPAct/V2/E-89 fuel property data set is provided in Appendix E. Red 

cell fill color in Appendix E tables indicates outliers. Orange fill color denotes data which were 

not used in the calculation of parameter averages. The latter occurred when a T50 and/or a T90 

result was an outlier or when sample contamination was suspected. 

The final set of Phase 3 EPAct/V2/E-89 test fuel properties to be used in emissions 

modeling is provided in Tables III-8 and III-9. Their values were computed using the round 

robin test data provided in Appendix E following the elimination of outliers. Table III-9 lists the 

properties of E0-E20 fuels, while Table III-10 those of the E85 fuel 29. 
31 

Table III-9. Final properties of E0-E20 Phase 3 EPAct/V2/E-89 fuels based on round robin results. 

1 2 3 4 5 6 7 8 9 10 11 12 13 14

Density, 60o

F g/cm3 D4052 0.7211 0.7220 0.7350 0.7346 0.7573 0.7342 0.7208 0.7191 0.7454 0.7644 0.7596 0.7517 0.7540 0.7223

API Gravity, 60o

F o

API D4052 64.6 64.3 60.8 60.9 55.2 61.1 64.6 65.1 58.2 53.4 54.6 56.5 56.0 64.2

Ethanol vol. % D5599 10.03 <0.10 10.36 9.94 <0.10 10.56 <0.10 <0.10 <0.10 9.82 10.30 9.83 <0.10 <0.10

Total Content of Oxygenates Other 

Than Ethanol vol. % D5599 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10

Distillation IBP oF 92.9 83.5 106.4 89.9 94.1 106.7 100.1 83.7 85.3 104.7 92.0 91.3 96.6 100.4

5% evap oF 112.5 105.4 136.0 115.9 128.6 130.4 127.6 108.1 105.1 130.0 115.4 110.7 127.0 126.5

10% evap oF 117.3 121.7 141.7 126.3 145.4 135.9 137.0 123.4 115.1 136.3 124.4 116.9 139.8 135.5

20% evap oF 123.9 154.4 148.9 140.9 172.6 142.6 149.0 151.6 130.3 144.3 137.6 125.0 158.7 147.3

30% evap oF 131.2 190.6 155.0 151.7 199.4 148.3 161.7 185.1 147.2 151.0 148.1 133.8 178.2 160.0

40% evap oF 139.9 218.5 175.1 161.2 222.1 153.4 176.6 204.4 167.7 161.6 156.5 142.8 199.9 175.1

50% evap oF 148.9 236.7 217.5 221.9 237.0 188.5 193.1 221.1 192.8 217.1 189.3 152.2 222.5 192.8

60% evap oF 172.3 252.7 230.2 245.9 247.2 228.2 210.2 233.5 224.7 261.5 231.1 198.5 245.2 212.0

70% evap oF 224.1 271.7 243.6 270.0 258.5 267.7 228.6 246.4 260.3 290.4 251.4 275.1 269.8 237.3

80% evap oF 254.6 305.9 257.1 303.5 273.1 310.1 251.5 264.0 292.2 317.5 270.0 307.9 303.5 280.1

90% evap oF 300.2 340.1 295.9 337.5 300.0 340.4 298.4 303.1 341.8 340.2 298.6 339.8 337.9 338.5

95% evap oF 334.5 353.0 334.4 352.0 323.5 352.7 329.3 330.5 363.5 354.3 325.0 357.7 354.4 354.5

FBP oF 368.0 375.3 368.9 369.8 357.8 369.2 361.8 360.9 384.7 372.4 360.8 375.9 377.5 377.5

DVPE (EPA equation) psi D5191 10.07 10.20 6.93 10.01 6.95 7.24 7.15 10.20 10.30 7.11 9.93 10.13 6.92 7.14

Aromatics vol. % D1319 15.4 14.1 15.0 15.5 34.7 15.0 17.0 15.7 35.8 34.0 35.0 34.8 34.1 16.9

Olefins vol. % D1319 7.6 6.8 7.6 6.8 6.9 8.8 7.5 6.4 6.2 6.1 6.9 6.9 6.3 8.5

Saturates vol. % 100 - D1319Aromatics - 

D1319Olefins - D5599Ethanol 67.0 79.1 67.0 67.8 58.4 65.6 75.5 78.0 58.0 50.1 47.8 48.5 59.6 74.6

Benzene vol. % D3606 0.62 0.51 0.61 0.54 0.51 0.68 0.55 0.50 0.54 0.52 0.54 0.57 0.51 0.52

S mg/kg D5453 30 23 22 21 24 23 23 23 23 25 24 19 23 24

RON - D2699 94.8 96.0 98.0 97.1 96.7 96.3 91.2 95.5 94.5 98.5 97.8 100.4 95.8 91.5

MON - D2700 86.3 88.6 87.6 87.6 86.3 86.6 84.2 87.8 84.8 87.2 85.6 88.0 85.8 84.6

(RON+MON)/2 - - 90.6 92.3 92.8 92.4 91.5 91.5 87.7 91.7 89.7 92.9 91.7 94.2 90.8 88.1

C mass % D5291 mod.* 81.70 85.12 81.61 82.21 86.58 81.52 85.16 85.12 87.03 83.47 83.68 83.32 86.76 85.28

H mass % D5291 mod.* 14.02 14.43 14.17 14.12 12.92 14.21 14.25 14.32 12.82 12.83 12.61 12.68 13.15 14.29

O mass % D5599 3.9 <0.1 3.9 3.7 <0.1 4.0 <0.1 <0.1 <0.1 3.6 3.7 3.6 <0.1 <0.1

Net Heat of Combustion MJ/kg D4809 41.950 43.960 41.536 41.952 42.948 41.785 43.735 44.037 43.209 41.210 41.175 41.373 43.171 43.519

Water mass % E-1064 0.071 0.010 0.059 0.077 0.014 0.073 0.019 0.020 0.009 0.067 0.066 0.066 0.014 0.015

Lead g/l D3237 - <0.001 - - <0.003 - <0.001 0.001 <0.001 <0.003 - <0.003 <0.001 <0.001

Copper Strip Corrosion - D130 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A

Solvent Washed Gum Content mg/100ml D381 <0.5 <0.5 <0.5 1.5 <0.5 <0.5 <0.5 <0.5 <0.5 <0.5 0.5 <0.5 1.5 <0.5

Oxidation Stability min. D525 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240

* Method adapted by individual laboratories to testing of gasolines

FUEL

D86 (OptiDist or equivalent for 

E10, E15 and E20 fuels)

PROPERTY UNIT TEST METHOD
32 

Table III-9 Cont. Final properties of E0-E20 Phase 3 EPAct/V2/E-89 fuels based on round robin results. 

15 16 20 21 22 23 24 25 26 27 28 30 31

Density, 60o

F g/cm3 D4052 0.7428 0.7636 0.7425 0.7754 0.7371 0.7476 0.7422 0.7702 0.7593 0.7434 0.7699 0.7508 0.7742

API Gravity, 60o

F o

API D4052 58.8 53.6 58.9 50.8 60.3 57.6 58.9 52.0 54.6 58.6 52.1 56.8 51.1

Ethanol vol. % D5599 <0.10 10.76 20.31 20.14 20.51 20.32 20.51 20.03 15.24 14.91 14.98 9.81 20.11

Total Content of Oxygenates Other 

Than Ethanol vol. % D5599 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10 <0.10

Distillation IBP oF 84.7 104.5 107.9 106.3 89.8 109.0 89.7 89.0 88.7 104.8 103.9 90.9 105.8

5% evap oF 105.5 133.0 137.3 134.7 118.8 133.3 115.9 113.7 109.6 135.3 136.3 110.3 132.5

10% evap oF 115.6 139.2 142.6 141.3 129.6 138.9 126.9 125.5 117.1 142.3 144.2 116.7 139.1

20% evap oF 130.5 147.8 149.7 150.3 144.3 146.2 142.8 142.1 127.8 152.0 154.0 125.4 147.7

30% evap oF 146.6 155.1 155.3 157.1 153.7 152.3 153.2 153.3 138.6 158.0 160.2 133.9 155.1

40% evap oF 166.3 172.1 159.6 162.6 159.5 157.8 160.4 160.9 149.8 163.8 165.8 143.1 161.3

50% evap oF 189.7 218.8 162.7 167.6 163.2 162.5 165.1 166.9 160.3 221.5 216.6 152.9 167.3

60% evap oF 216.2 237.5 179.9 217.3 167.2 171.6 172.9 191.3 174.7 265.1 240.2 197.2 214.0

70% evap oF 243.0 251.9 234.8 255.2 233.9 270.9 266.1 281.6 277.0 274.9 251.6 267.3 271.6

80% evap oF 265.9 268.6 253.1 275.3 253.6 311.4 305.5 310.3 306.5 311.3 268.4 294.6 297.0

90% evap oF 299.4 300.6 298.7 305.0 297.3 338.2 338.1 337.9 338.7 340.3 298.8 323.8 325.2

95% evap oF 329.3 330.8 336.6 331.3 334.5 350.0 350.3 352.7 356.7 351.9 327.3 341.8 342.1

FBP oF 363.7 365.6 371.9 360.5 369.9 364.6 368.2 371.8 377.3 372.2 363.2 366.1 365.6

DVPE (EPA equation) psi D5191 10.23 7.12 6.70 7.06 10.21 6.84 10.12 10.16 10.21 6.97 6.87 10.23 6.98

Aromatics vol. % D1319 35.3 35.6 15.2 35.5 15.0 15.9 15.3 35.2 35.6 14.9 34.5 35.5 35.5

Olefins vol. % D1319 7.2 6.8 7.4 7.1 6.9 7.5 7.3 6.6 6.5 7.4 7.0 6.5 6.8

Saturates vol. % 100 - D1319Aromatics - 

D1319Olefins - D5599Ethanol 57.4 46.9 57.1 37.3 57.6 56.4 56.9 38.1 42.7 62.9 43.5 48.2 37.6

Benzene vol. % D3606 0.54 0.62 0.61 0.61 0.59 0.63 0.62 0.65 0.62 0.56 0.59 0.58 0.60

S mg/kg D5453 24 23 22 22 21 21 21 26 23 26 24 23 25

RON - D2699 95.0 101.0 101.9 101.4 101.8 97.4 100.8 102.2 101.7 100.8 102.7 100.5 101.7

MON - D2700 84.9 88.3 89.3 87.5 89.3 86.8 88.6 88.3 88.5 89.2 89.4 88.1 88.2

(RON+MON)/2 - - 90.0 94.7 95.6 94.5 95.6 92.1 94.7 95.3 95.1 95.0 96.1 94.3 95.0

C mass % D5291 mod.* 86.88 83.40 78.06 79.90 78.24 78.34 78.47 80.62 81.48 80.27 81.78 83.17 79.90

H mass % D5291 mod.* 12.79 12.66 14.01 12.43 13.85 13.86 13.86 12.38 12.45 14.01 12.62 13.00 12.49

O mass % D5599 <0.1 3.9 7.6 7.1 7.7 7.5 7.6 7.2 5.6 5.5 5.4 3.6 7.2

Net Heat of Combustion MJ/kg D4809 43.108 41.013 40.057 39.285 40.031 39.915 40.114 38.855 40.384 41.062 40.383 41.304 39.391

Water mass % E-1064 0.012 0.066 0.138 0.128 0.113 0.112 0.108 0.117 0.088 0.090 0.091 0.086 0.143

Lead g/l D3237 <0.001 - <0.003 0.009 0.004 <0.003 0.005 0.001 <0.003 <0.003 <0.003 - <0.003

Copper Strip Corrosion - D130 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A 1A

Solvent Washed Gum Content mg/100ml D381 0.5 1 <0.5 0.5 <0.5 0.5 0.5 <0.5 <0.5 0.5 <0.5 <0.5 0.5

Oxidation Stability min. D525 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240 >240

* Method adapted by individual laboratories to testing of gasolines

D86 (OptiDist or equivalent for 

E10, E15 and E20 fuels)

FUEL

PROPERTY UNIT TEST METHOD
33 

Table III-10. Final properties of the E85 Phase 3 EPAct/V2/E-89 fuel. 

 Density, 60oF g/cm3 D4052 0.7797

 API Gravity, 60oF oAPI D4052 49.8

 Uncorrected Ethanol mass % D5501 mod.* 79.59

 Uncorrected Methanol mass % D5501 mod.* 0.01

 Ethanol vol. % D5501 mod.* 77.15

 Methanol vol. % D5501 mod.* <0.01

 Estimated Hydrocarbon 

Content vol. % 100 - D5501Ethanol - E203Water 22.14

 Distillation IBP oF 99.0

5% evap oF 132.9

10% evap oF 154.3

20% evap oF 167.6

30% evap oF 170.3

40% evap oF 171.2

50% evap oF 171.8

60% evap oF 172.1

70% evap oF 172.5

80% evap oF 172.9

90% evap oF 173.9

95% evap oF 176.2

FBP oF 265.8

 DVPE (EPA equation) psi D5191 8.92

 Benzene vol. % D5580 0.12

 S mg/kg D5453 16

 C mass % D5291 mod.** 57.74

 H mass % D5291 mod.** 12.80

 O mass % D5501 mod.* 27.19

mass % E203 0.93

vol. % E203 0.72

 Net Heat of Combustion MJ/kg D4809 30.058

 Solvent Washed Gum mg/100 ml D381 1.9

 Unwashed Gum mg/100 ml D381 1.8

 Acidity (as acetic acid) mass % D1613 0.0021

 pHe - D6423 8.08

 Inorganic Chloride mg/kg D7319 Not detected

 Copper mg/l D1688 modified as outlined in D4806 0.02

 * Method adapted by individual laboratories to testing of E85 fuels

 ** Method adapted by individual laboratories to testing of gasolines

D86

 Water

PROPERTY UNIT TEST METHOD Average
34 

Figure III-3. Ethanol content of Phase 3 EPAct/V2/E-89 fuels. 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 20 21 22 23 24 25 26 27 28 30 31

Fuel Designation

0

10

20

Ethanol Content, vol. %
35 

Figure III-4. Distillation curves of E0 Phase 3 EPAct/V2/E-89 fuels. 

0 10 20 30 40 50 60 70 80 90 100

% Evaporated

50

100

150

200

250

300

350

400

Temperature, o

F

Fuel Designations:

2 5 7 8

9 13 14 15
36 

Figure III-5. Distillation curves of E10 Phase 3 EPAct/V2/E-89 fuels. 

0 10 20 30 40 50 60 70 80 90 100

% Evaporated

50

100

150

200

250

300

350

400

Temperature, o

F

Fuel Designations:

1 3 4 6 10

11 12 16 30
37 

Figure III-6. Distillation curves of E15, E20 and E85 Phase 3 EPAct/V2/E-89 fuels. 

0 10 20 30 40 50 60 70 80 90 100

% Evaporated

50

100

150

200

250

300

350

400

Temperature, o

F

Fuel Designations:

26 27 28 20 21 22

23 24 25 31 29

E85
38 

Figure III-7. DVPE of Phase 3 EPAct/V2/E-89 fuels. 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 20 21 22 23 24 25 26 27 28 30 31

Fuel Designation

6

7

8

9

10

11

DVPE, psi
39 

Figure III-8. Aromatic content of Phase 3 EPAct/V2/E-89 fuels. 

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 20 21 22 23 24 25 26 27 28 30 31

Fuel Designations

10

20

30

40

Aromatic Content, %v
40 

IV. TEST VEHICLE FLEET SIZING AND SELECTION

A. Fleet Selection 

 Emission behavior of vehicles originally meeting Tier 0 and Tier 1 emission standards 

(generally, those sold in the 1990s) is well-characterized in databases supporting the Complex 

Model for gasoline production compliance and the Agency’s California oxygenate waiver 

decision.12 Together, these databases contain thousands of measurements taken on hundreds of 

vehicles and fuel blends. At the time this program was being designed, only a limited amount of 

fuel effect data existed for vehicles meeting the Tier 2 standards, data that would be required by 

Congress as highlighted in Section II. Thus, the focus of this program was on filling that data 

gap. 

 1. Statistical Determination of Number of Vehicles 

 Proper design of an experimental study should ensure that the effect being investigated 

has a good chance of being detected if it exists. This likelihood of detection is referred to as the 

statistical power of a study. Estimation of power requires specification of a size of effect 

deemed to be meaningful, as well as information about the variability or noise that will occur in 

the measurements. These inputs may be informed by previous experiments or, if no such data is 

available, more arbitrarily chosen based on some assumptions about the behavior of the test 

subjects.

A power analysis was performed during the initial design of this program to estimate the 

number of vehicles required to detect a fuel effect of various sizes for both hydrocarbon and 

NOx emissions. The statistical methods were based on those presented by Snedecor and 

Cochran, and are consistent with work done for the Auto/Oil Air Quality Improvement Research 

Program (AQIRP) in the early 1990s.13,14 Table IV-1 shows estimates of vehicle-by-fuel 

 

12 See footnote 1. 13 Snedecor G.W. & Cochran W.G., “Statistical Methods”, Iowa State Univ Press, 8th Ed.,1989. 14 See Painter, J.L. & Rutherford, J.A., “Statistical Design and Analysis Methods for the Auto/Oil Air Quality 

Improvement Research Program”, SAE paper number 920319.
41 

variability and repeat measurement error derived from data collected in recent emission 

programs. 

Table IV-1. Data used in vehicle selection power analysis.

Study NOx NMHC

Vehicle-by-fuel variability (% as COV)

CRC E-67 2 18

2005-6 MSAT 14 13

Value used 14 18

Test-to-test repeatability (% as COV)

CRC E-67 20 19

2006 CARB 22 17

2005-6 MSAT 15 17

CRC-E74b 22 20

Value used 22 20

 

 The prior test programs shown here were conducted in a variety of configurations and 

were included to give an idea of the range of values expected. CRC E-67 and E-74b represent 

testing on different vehicles and fuels performed at the same laboratory. The 2005-6 MSAT 

program tested different vehicles and fuels at different laboratories. The 2006 CARB data 

represent testing of the same vehicle on the same fuel at different laboratories. Examination of 

both NOx and hydrocarbon emissions allowed the design to accommodate the more restrictive of 

the two. 

These two measures of variability were combined to compute the vehicle-by-fuel 

standard error was computed as follows, where n is the number of replicates assumed. 

SEvehicle by fuel = �variability2 + repeatability2

n
42 

The initial vehicle selection done for Phase 1 of the program assumed a power of 0.90 and a 

significance level of 0.05 for the statistical tests. Thus, the following equation was used to 

estimate the number of samples (test vehicles) required, denoted here as r: 15

r = 1 + 10.5 �2 � SEvehicle byfuel

relative difference�

2

�

Table IV-2 shows an example of the results run for different numbers of replicates and relative 

differences detectable between two treatments (e.g., 0.25 = 25% fuel effect). 

Table IV-2. Results of power analysis for number of vehicles to test.

Replicates SEvehicle by fuel Relative difference Vehicles at 0.90 power

1 0.270 0.05 614

0.10 155

0.15 70

0.20 40

0.25 26

0.40 11

2 0.230 0.05 446

0.10 113

0.15 51

0.20 29

0.25 19

0.40 8

3 0.215 0.05 389

0.10 98

0.15 45

0.20 26

0.25 17

0.40 8

A relative fuel effect of 25% was selected during the design of AQIRP as a reasonable 

size of effect to investigate. Using this level of effect, a design of 19 vehicles with two replicates 

for each fuel-vehicle combination was originally chosen to meet a 90% study power. This 

number seemed large, considering that anti-backsliding policy discussions at the time of this 

study design were focusing on NOx emission changes on the order of 5-10% that occurred when 

 

15 For more details on this calculation, see Snedecor & Cochran, 1989, p. 102-105. 
43 

ethanol was added to gasoline in previous studies on older vehicles. However, there was an 

expectation that through careful design and execution, this program could achieve better 

measurement variability and repeatability than suggested by previous programs, which would 

allow adequate statistical power with smaller sample size (something that could not be known 

until after data collection was underway). Additionally, the program budget would not have 

accommodated the hundreds of test vehicles suggested by the calculation to detect relative 

differences below 10%. 

 2. Criteria Based on Sales, Engine Size, Technology, etc. 

The Phase 1 fleet of 19 test vehicles was chosen with the intent of being representative of 

latest-technology light duty vehicles being sold at the time the program was being launched. In 

terms of regulatory standards, the test fleet was to conform on average to Tier 2 Bin 5 exhaust 

levels and employ a variety of emission control technologies, to be achieved by including a range 

of vehicle sizes and manufacturers. 

Engine family sales data obtained from EPA certification and Wards databases was 

analyzed to generate a list of high-sales vehicles as candidates for inclusion.16 Grouping sales 

data by engine family allowed additional transparency and flexibility in choosing test vehicles 

that represent a wider group than one specific make and model. The resulting test fleet, shown in 

Table IV-3, was used in Phases 1-2 of the program and the engine families represented were 

expected to cover more than half of new vehicle sales for MY 2008. No criteria were used by 

the sponsors to select the individual test vehicles for lease, and thus this selection was effectively 

random. 

 

16 Engine family is a term used in manufacturing and certification to describe a combination of a base engine and 

after-treatment system that may be used in several vehicle makes and models offered by a manufacturer.
44 

Table IV-3. Test vehicle fleet used in Phases 1 and 2 (19 vehicles).

Model 

Year Make Brand Model Program ID

Engine 

Size Engine Family Tier 2 Cert Bin

2008 GM Chevrolet Cobalt CCOB 2.2L I4 8GMXV02.4025 5

2008 GM Chevrolet Impala FFV CIMP 3.5L V6 8GMXV03.9052 5

2008 GM Saturn Outlook SOUT 3.6L V6 8GMXT03.6151 5

2008 GM Chevrolet Silverado FFV CSIL 5.3L V8 8GMXT05.3373 5

2008 Toyota Toyota Corolla TCOR 1.8L I4 8TYXV01.8BEA 5

2008 Toyota Toyota Camry TCAM 2.4L I4 8TYXV02.4BEA 5

2008 Toyota Toyota Sienna TSIE 3.5L V6 8TYXT03.5BEM 5

2008 Toyota Toyota Tundra TTUN 4.0L V6 8TYXT04.0AES 5

2008 Ford Ford Focus FFOC 2.0L I4 8FMXV02.0VD4 4

2008 Ford Ford Taurus FTAU 3.5L V6 8FMXV03.5VEP 5

2008 Ford Ford Explorer FEXP 4.0L V6 8FMXT04.03DB 4

2008 Ford Ford F150 FFV F150 5.4L V8 8FMXT05.44HF 8

2008 Chrysler Dodge Caliber DCAL 2.4L I4 8CRXB02.4MEO 5

2008 Chrysler Dodge Caravan FFV DCAR 3.3L V6 8CRXT03.3NEP 8

2008 Chrysler Jeep Liberty JLIB 3.7L V6 8CRXT03.7NE0 5

2008 Honda Honda Civic HCIV 1.8L I4 8HNXV01.8LKR 5

2008 Honda Honda Accord HACC 2.4L I4 8HNXV02.4TKR 5

2008 Honda Honda Odyssey HODY 3.5L V6 8HNXT03.54KR 5

2008 Nissan Nissan Altima NALT 2.5L I4 8NSXV02.5G5A 5

 3. Reduction of Fleet for Phase 3

 

 Due to budget constraints that arose after beginning Phase 3, the fleet was reduced to 15 

vehicles from the 19 used in Phases 1-2. (One additional vehicle, the Dodge Caravan, was used 

only for E85 testing to provide a total of four FFVs tested in the program.) A study power 

analysis was repeated using data from 15 vehicles in Phase 1, and results suggested a power in 

the range of 0.7-0.8 for detecting a 25% relative difference at a significance level of 0.05. 

(Relaxing the significance level to 0.10 will increase the study power. Statistical analysis of 

Phase 1 data found significant fuel effects smaller than 25%, so this shouldn’t be understood as a 

lower limit of detectable effects, but rather as a screen for the largest effect that is unlikely to be 

missed.) 

 

 Reduction of the fleet meant choosing four vehicles to eliminate. Primary considerations 

in this process included retaining high-sales engine families, a balance of vehicle and engine 

sizes, and maintaining representation of all manufacturers originally included in order to 

represent a range of technologies and emission control strategies. There was also consideration 
45 

of the fact that changes in the test fleet could shift the average program results. As a screen for 

this issue, all nineteen vehicles were ranked according to their NOx and NMHC sensitivity to 

fuel ethanol level based on the Phase 1 data, with the intent being to avoid removing several 

vehicles with similar emissions behavior (though the two pollutants could provide conflicting 

direction). Table IV-4 shows the resulting set of vehicles used to generate the Phase 3 data. 

Note that the Dodge Caravan was used only for E85 testing, so that 15 vehicles were used to 

produce the matrix of 27 fuels. 

Table IV-4. Reduced vehicle fleet used for Phase 3.

 4. Vehicle Procurement and Delivery

GM 2008 Chevrolet Cobalt CCOB 2.4L I4 8GMXV02.4025 5 NA 4,841

GM 2008 Chevrolet Impala FFV CIMP 3.5L V6 8GMXV03.9052 5 L2 5,048a

GM 2008 Saturn Outlook SOUT 3.6L V6 8GMXT03.6151 5 L2 5,212a

GM 2008 Chevrolet Silverado FFV CSIL 5.3L V8 8GMXT05.3373 5 NA 5,347b

Toyota 2008 Toyota Corolla TCOR 1.8L I4 8TYXV01.8BEA 5 U2 5,019a

Toyota 2008 Toyota Camry TCAM 2.4L I4 8TYXV02.4BEA 5 U2 4,974b

Toyota 2008 Toyota Sienna TSIE 3.5L V6 8TYXT03.5BEM 5 U2 4,997

Ford 2008 Ford Focus FFOC 2.0L I4 8FMXV02.0VD4 4 U2 5,150a,b

Ford 2008 Ford Explorer FEXP 4.0L V6 8FMXT04.03DB 4 NA 6,799c

Ford 2008 Ford F-150 FFV F150 5.4L V8 8FMXT05.44HF 8 NA 5,523a

Chrysler 2008 Dodge Caliber DCAL 2.4L I4 8CRXB02.4MEO 5 NA 4,959

Chrysler 2008 Dodge Caravan FFVd DCAR 3.3L V6 8CRXT03.3NEP 8 NA 5,282

Chrysler 2008 Jeep Liberty JLIB 3.7L V6 8CRXT03.7NE0 5 NA 4,785

Honda 2008 Honda Civic HCIV 1.8L I4 8HNXV01.8LKR 5 U2 4,765

Honda 2008 Honda Odyssey HODY 3.5L V6 8HNXT03.54KR 5 U2 4,850

Nissan 2008 Nissan Altima NALT 2.5L I4 8NSXV02.5G5A 5 L2 5,211b

 a – These vehicles were added to the Phase 3 test matrix at a later date. Prior to their inclusion in the matrix, they received on-road 

miles every other week. 

 b – These vehicles were included in an FTP interim test program (EPA WA 1-09) conducted between Phases 1 and 2.

 c – During Phase 1, the initial 4,000 miles of vehicle break-in was conducted with the wrong crankcase lubricant viscosity grade. An 

additional 2,000-mile break-in was conducted with the correct lubricant viscosity grade.

 d – Dodge Caravan FFV was only tested with E85

MAKE

MO DEL 

YEAR BRAND MO DEL

VEHICLE 

NAME ENGINE

ENGINE 

FAMILY

EPA T2 

BIN

CA 

CERT

PHASE 3 

STARTING 

O DO METER
46 

 Vehicles for this program were obtained brand new and delivered to the SwRI facility in 

San Antonio, Texas, where testing took place. All vehicles were leased by SwRI for two years at 

the initiation of Phase 1 of the V2/EPAct/E-89 program. Due to changes and additions to the 

overall program, the term of the two-year leases expired prior to the completion of all Phase 3 

testing. The Coordinating Research Council then purchased the test vehicles and made them 

available to the test program for the remainder of its duration.

B. Initial Preparation and Storage

 1. Mileage Accumulation and Conditioning of Engine Oil

Prior to commencement of emission testing for Phase 1 of the program, each vehicle was 

brought up to 4,000 odometer miles, the intent being to avoid variability in emissions behavior 

occurring during engine break-in. This was accomplished by operating the vehicles on mileage 

accumulation dynamometers over the Standard Road Cycle using a non-oxygenated, 

commercially-acquired, 87 octane gasoline (see Table IV-5). 

Engine crankcase oil meeting GF-4 specifications was provided for the program by the 

Lubrizol Corporation. Engine oil was drained and replaced with the appropriate manufacturerrecommended viscosity grade at the start of mileage accumulation, and again after 2,000 miles. 

The 2,000-mile fill remained in the test vehicles throughout Phases 1, 2, and 3 of the program. 

Each vehicle’s oil sump was overfilled by 12 ounces at the 2,000-mile oil change to 

accommodate oil samples to be taken during the course of the program (see Section V.C.2 for 

more details on oil sampling). The vehicle odometer readings at the start of Phase 3 are included 

in Table IV-4. 
47 

Table IV-5. Properties of mileage accumulation fuel. 

a. Effect of Oil Age on Emissions 

 A study completed by EPA and Lubrizol shortly before the start of this program 

examined the effect of oil age on emissions.17 The study involved accumulating 2000 miles on 

two low-mileage, Tier-2-compliant vehicles using a non-ethanol fuel, with emission 

measurements taken immediately after oil change and at 500, 1000, and 2000 miles. The only 

significant effect of oil age observed was for PM, which dropped by nearly half after 500 miles

in one of the vehicles. Both vehicles showed a general trend of PM reduction out to 2000 miles, 

though differences between each test interval were not large or statistically significant. 

 The study also looked at the effect of mileage accumulation using ethanol-blended fuel 

on emissions and oil quality. After the initial 2000-mile accumulation period on E0, the fuel 

 

17 Christianson, M., Bardasz, E., and Nahumck, B. Impact of Lubricating Oil Condition on Exhaust Particulate 

Matter Emissions from Light Duty Vehicles. Society of Automotive Engineers International Journal of Fuels and 

Lubricants, December 2010 issue 3: pp. 476-488.

Density, 60oF g/cm3 D4052 0.7329

API Gravity, 60oF o

API D4052 61.5

Ethanol Content vol. % D5599 <0.1

IBP oF D86 82

T10 oF D86 109

T50 oF D86 194

T90 oF D86 342

FBP oF D86 416

DVPE psi D5191 11.1

Aromatics vol. % D1319 26.2

Olefins vol. % D1319 7.7

Benzene vol. % D3606 0.95

S mg/kg D5453 15.9

(R + M)/2 - Calc. 87.5

Net Heat of Combustion Btu/lb D4809 18,734

UNIT METHOD Valero 

RUL PROPERTY
48 

supply was changed to E10, and another 3000 miles were accumulated. No significant changes 

were seen in emissions between the beginning and end of the period, and an analysis of oil 

quality (including metals, acid and base numbers) done by Lubrizol didn’t show oil degradation 

beyond the normal range for the accumulated mileage. 

 Though this study was relatively small, it was intended to serve as a screening, 

confirming that 2000 miles of oil age should be sufficient to stabilize emissions, and that use of 

ethanol fuels didn’t appear to cause unacceptable levels of oil degradation. 

 2. Vehicle Storage Conditions During the Program 

Vehicles being actively tested were stored indoors in a temperature-controlled soak area 

adjacent to the test cell. All vehicles had batteries trickle-charged for at least 12 hours prior to 

testing. Due to the nature of the randomized test matrix, as well as the incremental addition of 

test vehicles to the program, certain vehicles were not involved in active testing for several 

weeks at a time. Those not scheduled to test for approximately two weeks or more were 

generally stored outdoors in a parking area near the test facility. In an attempt to minimize 

vehicle maintenance issues due to extended inactivity, those vehicles were operated by an 

experienced driver once every two weeks over an on-road course around the perimeter of the 

SwRI campus. Prior to each drive, each vehicle received a brief visual inspection to ensure 

proper tire inflation and fluid levels. One “lap” was completed, which was approximately 8 

miles in length and about 20 minutes in duration. Speed limits ranged from 35 to 45 mph, and 

the drive included six traffic signals and two stop signs. This task was conducted using a nonethanol fuel. 
49 

V. TEST PROCEDURES, DATA COLLECTION, ISSUES ENCOUNTERED 

There are many things that can affect vehicle emissions performance, with the fuel effect 

potentially being a relatively small factor. Thus, an important consideration in fuel effects 

studies is the need to minimize measurement artifacts, which include variability, error, or bias in 

the results that are unintended in the design of the study. Any such artifacts become confounded 

with the fuel effect itself, which can lead to loss of statistical power to resolve an effect or, 

perhaps worse, detection of an effect that doesn’t exist. As new vehicles have lower and lower 

emission levels, more and more sources of measurement artifacts have the potential to become 

influential in the results of the study. A great deal of effort was taken in the design and 

execution of this program to minimize artifacts related to procedures, including following a 

particular sequence of steps in vehicle handling before, during, and between emission tests, as 

well as use of the same driver and test cell for all emission tests. Such procedures are described 

in more detail in this section. (Another potential source of error in fuel effects models is fuel 

property measurement error; the fuels round robin process described in Section III was done to 

minimize this.) 

 

A. Test Cycle, Conditions, and Schedule 

 All vehicle/fuel combinations were tested using the California Unified Cycle, also known 

as the LA92. This cycle was chosen because it contains higher speeds and acceleration rates 

representative of a wider range of typical driving behavior than what is covered in the FTP cycle. 

For this program, the LA92 was conducted as a three-phase, cold-start test in a manner similar to 

the FTP.

18 Test procedure quality controls included criteria for maximum deviation in speed and 

time from the test cycle driving trace to minimize effect of driver behavior on test-to-test 

variability.

 Testing was conducted during the day shift while vehicle preparation, fuel changes, and 

conditioning were conducted during a second shift. All vehicle soaks and tests were conducted 

 

18 In order to supplement data being collected during Phase 4 of this test program, the four FFVs were also tested 

over the FTP cycle when operating on E85.
50 

at a nominal temperature of 72°F. The representative bulk oil temperature of a vehicle’s sump 

was stabilized to 72°F ± 3°F prior to conducting any emission test to minimize any effect of 

temperature on variability. 

SwRI made a number of modifications and optimizations to the test cell air handling 

system during the initial phases of the program in an effort to maintain vehicle intake air 

humidity at 75 ± 5 grains H2O/lb dry air while tests were being conducted, consistent with 

certification procedures in 40 CFR Part 86, to minimize the impacts on NOx emissions.19 

During Phase 3 and later portions of the program, this target was met 95% of the time, with some 

exceptions when outdoor weather conditions were rapidly changing. SwRI provided a humidity 

quality check metric within each individual test file and flagged entries in the test log where 

humidity was outside the desired range for more than five percent of the time. EPA and NREL 

provided guidance to SwRI regarding whether or not any individual test should be repeated. 

 Under Phase 1 of the program, SwRI determined and verified PM sample flow rates that 

provided proportionality. Those same flow rates were used for Phase 3. The CVS blower was 

turned on approximately 20 minutes before each emission test in an effort to ensure tunnel 

stability.

 1. Test Matrix

The test matrix was designed to test each vehicle/fuel combination in a randomized order

to minimize any effects of biases or artifacts that may not have been addressed through other 

provisions in design or procedures (e.g., possible effects of season, weather, changes in test fuel 

properties over time, vehicle or instrument drift, etc.). During the first nine weeks of testing, 

EPA specified partially randomized vehicle/fuel assignments that alternated between E0 and 

higher-ethanol blends in an effort to determine the amount of conditioning necessary to allow a 

vehicle’s fuel control system to adapt to a new ethanol concentration. Development of the 

vehicle conditioning procedure is discussed in further detail in Section V.B. Once this issue was 

 

19 The calculation of NOx emission rates includes a humidity correction factor, but providing consistent test 

conditions are preferable to relying on this factor alone.
51 

resolved, vehicle/fuel assignments were made using a spreadsheet tool that tracked which 

combinations had been tested and chose new assignments randomly from the remaining options. 

Testing started with five E0 fuels as shown in Table V-1. Additional fuels were added to 

the test matrix based on both the requirements of the vehicle conditioning assessment and on fuel 

availability (fuel blending and delivery took several months). All fuels became available to the 

randomization algorithm by the 12th week of testing. Due to initial funding limitations, only ten 

vehicles were included in the original Phase 3 test plan. Two additional vehicles were added to 

the matrix in the 25th week of testing, and three additional vehicles were added in the 37th week 

of testing. These additional vehicles were added to the test randomization scheme with 

randomized fuel/vehicle pairings from the outset. 

Table V-1. Schedule of addition of fuels and vehicles to the test matrix. 

Phase 3

Week

Fuels

Added

Vehiclesa

Added

Vehicle/Fuel

Assignments

Week 1 2, 7, 8, 9 and 15 CCOB, TCAM, FEXP, DCAL, 

HODY

EPA

Week 2 None CSIL, TSIE, DLIB, HCIV, NALT

Week 3 None None

Week 4 1, 12, 13 None

Week 5 None None

Week 6 22, 24 None

Week 7 None None

Week 8 3, 4, 5, 11, 14, 16, 20, 21, 23, 30 None

Week 9 None None

Week 10 None None Randomized for 

rest of program, 

except for E85

Week 12 6, 10, 25, 26, 27, 28, 31 None

Week 25 None FFOC, SOUT

Week 37 None CIMP, F150, TCOR

Week 55 29 (E85) DCAR Last fuel tested

Week 60 End of Phase 3 testing a - Vehicle designations are explained in Section IV.

Due to imperfect test-to-test repeatability and the possibility of individual tests to 

significantly influence results, each vehicle/fuel combination was tested at least twice, back-toback, with the second replicate usually performed on the following day. When replicates were 

split over weekends, an additional prep cycle was conducted as to maintain a 12-36 hr soak 

period. After two tests were completed and the acquired data passed all quality control 

verifications, the need for a third test was determined according to the variability criteria shown 
52 

in Table V-2. If the ratio of any of the specified pollutants (THC, NOX, or CO2) on a pair of tests 

for a given vehicle/fuel combination exceeded the levels shown in Table V-2, a third test was 

conducted and a note was made in the test log.

Table V-2. Repeatability criteria for third replicate. 

Dilute Gaseous 

Emission

Criterion For Requiring a Third 

Test (Composite Cycle 

Emissions)

CO2 Ratio of higher / lower > 1.03

NOX Ratio of higher / lower > 2.7

THC Ratio of higher / lower > 2.0

These repeatability criteria were generated based on variance levels found in Phase 1 

data, with a target of performing a third replicate for approximately 5% of fuel/vehicle pairs in 

Phase 3. This figure was chosen with the goal of covering a small number of measurements that 

might be statistical outliers. 

 Since emissions performance on current technology vehicles is dominated by what occurs 

shortly after start-up, engine cranking times between replicates were screened for inconsistency. 

If a test differed in cranking time from a previous replicate by more than one second, its 

procedure log and emissions data were reviewed by EPA and NREL to determine if an additional 

replicate should be performed. 

 In the end, additional replicates were performed for approximately 3% of vehicle/fuel 

combinations due to both repeatability and cranking criteria. (Some additional replicates beyond 

these were done as necessary to cover void tests or other procedural issues.) In the end, 926 fully 

valid tests were performed with all measurements as specified in the scope of work. Thirty 

additional tests had valid data for regulated pollutants but were missing other subsets of data

(e.g., speciation) due to measurement or data quality issues; inclusion of these (denoted as 

“makeup tests” and containing an “x” in the test number) brings the total number included in the 

database to 956. 
53 

B. Fuel Change and Vehicle Conditioning Procedures

 1. Learned Fuel Trim 

 The vehicles tested in this program all employed learned fuel adjustments (or trim) to 

continuously adjust the amount of fuel delivered for proper combustion. Most vehicle 

manufacturers began using such controls during the 1990s, and today nearly all new vehicles use 

microprocessor algorithms of varying sophistication to optimize vehicle performance and meet 

emission standards. 

 When the combustion process requires a change in air/fuel ratio, such as occurs when 

ethanol blend level changes, the engine controller must adjust the fuel trim to re-optimize engine 

and emission performance. This “re-learning” process requires operation of the vehicle for a 

certain period of time in several speed and load modes. Since this test program used multiple 

fuels with widely varying properties, sufficient prep procedures were needed to ensure emission 

behavior was stabilized after a fuel change.

 During all testing and prep procedures, vehicles were connected to an on-board 

diagnostics (OBD) scanner to capture data for parameters of interest, including those related to 

fuel trim. For more discussion of OBD data collection, refer to section V.D.3. 

 A vehicle fuel change and conditioning procedure was initially developed during Phases 

1 and 2. After those emissions and OBD data were analyzed, it was evident that the conditioning 

sequence was not sufficient for all vehicles to fully adapt after a change from E20 to E0 fuel. 

Therefore, the beginning of Phase 3 included a study (done concurrently with emission testing) 

to reassess and optimize the vehicle conditioning procedures. Long-term fuel trim (LTFT) and 

short-term fuel trim (STFT) OBD parameters were monitored during successive two-phase (bag 

1-2) LA92 test cycles and were analyzed for stabilization. Based on the results of this study, the 

CCOB, NALT, HCIV, HODY, and TCAM were all conditioned with five successive two-phase 
54 

LA92s starting in the third week of testing. For all the remaining vehicles, three LA92s was 

sufficient. Prior to the third week, all vehicles were conditioned with three LA92 preps. 

 The final vehicle fuel change and conditioning procedure is given in Table V-3. OBD 

data, including LTFT and STFT, were collected during all conditioning runs and made available 

to program sponsors as part of the program metadata. 

 2. Sulfur Purge 

 It is well known that fuel (and lubricant) sulfur content affects the performance of the 

exhaust aftertreatment catalyst. Vehicles emitting at lower and lower levels of regulated 

pollutants tend to rely on increasingly active catalysts, and thus there was concern that even a 

modest amount of sulfur contamination over time could produce a drift in emissions performance 

of the test vehicles that would be confounded with the fuel properties being studied. Thus, a set 

of high-speed and load cycles were performed after each fuel change in an effort to reset the 

vehicle catalysts back to some relatively “clean” baseline. The specific procedure used was 

taken from Appendix C of the CRC E-60 program report and consists of a series of alternating 

high and low speed cruises with hard accelerations in between.20

 

20 Durbin T.D., et al. (2003). The Effect of Fuel Sulfur on NH3 and Other Emissions from 2000-2001 Model Year 

Vehicles, Appendix C. Report number E-60. Coordinating Research Council, Alpharetta, GA. Available at 

www.crcao.org.
55 

Table V-3. Fuel change, conditioning, and test execution sequence. 

STEP DESCRIPTION

1 Drain vehicle fuel completely via fuel rail whenever possible. When switching to E85 only, drive vehicle 

to fully warm up engine.

2 Turn vehicle ignition to RUN position for 30 seconds (60 seconds when switching to E85) to allow 

controls to allow fuel level reading to stabilize. Confirm the return of fuel gauge reading to zero.

3 Turn ignition off. Fill fuel tank to 40% with next test fuel in sequence. Fill-up fuel temperature must be 

less than 50°F.

4 Start vehicle and execute catalyst sulfur removal procedure described in Appendix C of CRC E-60 

Program report. Apply side fan cooling to the fuel tank to alleviate the heating effect of the exhaust 

system. Engine oil temperature in the sump will be measured and recorded during the sulfur removal 

cycle.

5a Perform four vehicle coast downs from 70 to 30 mph, with the last two measured. If the individual run 

fails to meet the repeatability criteria established in Phases 1 and 2 of the program, the vehicle will be 

checked for any obvious and gross source of change in the vehicle’s mechanical friction. 

6 Drain fuel and refill to 40% with test fuel. Fill-up fuel must be less than 50°F.

7b Drain fuel again and refill to 40% with test fuel. Fill-up fuel must be less than 50°F.

8 Soak vehicle for at least 12 hours to allow fuel temperature to stabilize to the test temperature.

9c Move vehicle to test area without starting engine. Start vehicle and perform three 2-phase (bags 1 and 2) 

LA92 cycles. During these prep cycles, apply side fan cooling to the fuel tank to alleviate the heating 

effect of the exhaust system. Following the first two prep cycles, allow vehicle to idle in park for two 

minutes, then shut-down the engine for 2-5 minutes. Following the last prep cycle, allow the vehicle to 

idle for two minutes, then shut down the engine in preparation for the soak. 

10 Move vehicle to soak area without starting the engine.

11 Park vehicle in soak area at proper temperature (75 °F) for 12-36 hours. During the soak period, maintain 

the nominal charge of the vehicle’s battery using an appropriate charging device.

12 Move vehicle to test area without starting engine.

13 Perform LA92 cycle emissions test.

14 Move vehicle to soak area without starting the engine.

15 Park vehicle in soak area of proper temperature for 12-36 hours. During the soak period, maintain the 

nominal charge of the vehicle’s battery using an appropriate charging device.

16 Move vehicle to test area without starting the engine.

17 Perform LA92 emissions test.

18 Determine whether third replicate is necessary, based on data variability criteria (see Table V-2).

19 If a third replicate is required, repeat steps 14, 15, 16 and 17.

20 If third replicate is not required, return to step 1 and proceed with next vehicle in test sequence.

a – Vehicle coastdown repeatability criteria referred to in Step 5 were provided by EPA as follows:

• maximum difference of 0.5 seconds between back-to-back coastdown runs from 70 to 30 mph

• maximum ±7 percent difference in average 70 to 30 mph coastdown time from the running average for a 

given vehicle

b – Some vehicles received only two fuel drains and fills, i.e. Step 7 was skipped. See section V.F.4 for details.

c – Conduct five 2-phase LA92 test cycles for the following vehicles: CCOB, NALT, HCIV, HODY, and TCAM.

 3. Fuel Carryover in Vehicle Fuel Tanks
56 

 On May 27, 2009, (the 11th week of testing) SwRI noticed low levels of ethanol in 

exhaust speciation samples collected from the Nissan Altima on Fuel 13, which contained no 

ethanol. Samples were pulled from the drum used to fuel the vehicle, and from the vehicle’s fuel 

tank, and analyzed with a PetroSpec analyzer. The drum sample showed no ethanol while the 

vehicle's fuel tank showed 1.5 vol% ethanol, suggesting ethanol-containing fuel had carried over 

from a previous test in the Altima. The fuel tank sample was sent to EPA for analysis by ASTM 

D5599 method and was found to contain 1.44 vol% of ethanol. This was equivalent to a fuel 

carryover rate of 7.2% following two drains and 40% fills, meaning that approximately 3 gallons 

of the previous fuel (an E20) remained in the Altima’s tank after it has been drained via the fuel 

rail. From this point forward, except for mid- and end-point drift check tests, the Altima 

received three fuel flushes during the fuel change sequence.

 Investigating further, SwRI examined the speciation results for other vehicles and found 

measurable levels of ethanol when testing with an E0 fuel that was immediately preceded by an 

E20 fuel. To better understand this situation, fuel samples were collected during tests where fuel 

changed from an E15/E20 to an E0 fuel. D5599 analyses of the samples by SwRI and EPA 

suggested that the following percentages of the previous fuel were retained in the tanks of the 

test vehicles following fuel changes consisting of two drains and 40% fills: 

• Honda Odyssey: 8.8 vol% 

• Toyota Sienna: 5.0 vol% 

• Honda Civic: 4.2 vol% 

• Nissan Altima: 6.1 vol% 

• Toyota Camry: 5.3 vol% 

• All remaining vehicles: 2.1 to 3.2 vol% 

Based on these results, EPA and NREL directed SwRI to prepare several 95%/5% and 

5%/95% blends of the test fuels with the most extreme combinations of distillation properties 

and ethanol content to determine the effect of 5% fuel carryover on T50, T90 and RVP. The fuel 

sampling procedure used during these experiments is given in Appendix G, while the test matrix 
57 

and findings are given in Appendix H. The results of these experiments generally suggested that 

significant (nonlinear) deviations of T50 and T90 would not be expected as a result of carryover, 

but that shifts in RVP as high as 0.5 psi could be expected for E0 fuels experiencing ethanol 

contamination. 

Since the initial and subsequent carryover samples from the Altima were relatively 

inconsistent (3.7% vs. 7.2% carryover), SwRI performed additional refueling experiments with 

the Altima, Odyssey, Camry, Civic, and Sienna to determine the variability of the measurements. 

These experiments showed that a third fuel flush was effective in reducing fuel carryover to less 

than one percent. The procedure and results are given in Appendix I. Based on these results, 

starting on August 1, 2010, SwRI incorporated a third fuel drain and fill into the vehicle change 

procedure for the Altima, Odyssey, Sienna, Civic, and Camry to address larger carryover 

observed in their fuel systems. 

 Fuel carryover was characterized for the Focus, Outlook, Impala, F-150, and Corolla 

before they were added to the test matrix. Based on results, these five vehicles received triple 

drains and fills during fuel changes. 

 During investigation of fuel carryover, questions also arose about the impact of refueling 

location. Two sites were used during the drain and fill procedures, one with a noticeable slope 

toward the front of the vehicle, and the other toward one side. (Sloped pavement is typical in 

refueling areas, related to spill and storm water control.) Starting in August 2009, each vehicle 

was assigned a particular refueling location to attempt to limit any variability in carryover this 

may have caused. Prior to this, refueling may have occurred in either location. To assess the 

magnitude of effect of refueling location, additional experiments were conducted with the 

Silverado, Camry, Sienna, Caliber, Civic, Odyssey, and Altima. Results did not show any clear 

evidence of such effect. Additional details are given in Appendix J. 

 

C. Crankcase Oil Level Monitoring 
58 

Crankcase oil levels were checked monthly to ensure vehicles were operating as expected 

and that sufficient volume was available for collection of samples for analysis. No abnormalities 

in oil levels were noticed, with the exception of the Ford Explorer as described in section F.1. 

 Oil samples of four ounces in volume were collected from each vehicle at five points 

during Phase 3: at the start and end of the 2,000-mile lubricant break-in (i.e., around odometer 

readings of 2,000 and 4,000 miles), and following emissions testing of the 3rd, 15th, and 27th 

fuels in the Phase 3 test sequence. The oil samples were shipped in batches to Lubrizol for 

analysis. To accommodate the oil samples taken over the course of the program, each vehicle’s 

sump was overfilled by 12 ounces during the oil change at the mid-point of the 4,000-mile 

vehicle break-in. A summary timeline of oil changes and samples by approximate mileage is 

shown in Figure V-1, and details of dates and mileages at collection from each vehicle are given 

in Appendix F. 

Figure V-1. Summary of oil changes and sampling by odometer mileage. 

D. Emissions Measurements and Other Data Collection 

 Both bag-level and continuous emission measurements were collected during vehicle 

testing. On-board diagnostics (OBD) parameters relevant to engine operation and emissions 

were also recorded during testing. 
59 

 All emission tests were conducted using a Horiba 48-inch single-roll electric chassis 

dynamometer, which simulates the loads of acceleration, deceleration, and drag experienced by a 

vehicle when driving a test cycle. The computerized dynamometer control system uses a predefined mathematical formula with coefficients specific to each vehicle to simulate its behavior 

on the road. Vehicle manufacturers generate target road load coefficients for a vehicle (called 

target coefficients), which can then be used to compute set coefficients appropriate create an 

accurate simulation in other laboratories. The set coefficients for this program were derived 

from targets reported by manufacturers in EPA’s on-line certification database.

21 These values 

were approved by EPA prior to the initiation of testing, and are shown in Table V-4. 

Differences in electrical and mechanical characteristics and calibration of dynamometer 

equipment between test sites could be a source of variability in engine load that a vehicle 

experiences during a test, and thus the emissions it produces. Similarly, the vehicle driver has 

considerable influence on behavior of the engine during transient portions of the test cycle, also 

affecting emissions. Therefore, in an effort to minimize variability within the dataset, a single 

test site and a single driver were used for all data collected in the program, something that is 

unusual for a program of this size. Different drivers were used for sulfur purges and vehicle 

conditioning. Tension in the tie-downs used to secure the vehicle against the dynamometer roll 

was also maintained within a specified range for each test to minimize variability in tire drag and 

rolling friction.

 

21 More details on certification data are available at http://www.epa.gov/otaq/verify/index.htm
60 

Table V-4. Vehicle chassis dynamometer settings. 

 An additional step taken to ensure data quality was the performance of multiple coastdown checks for each vehicle during each fuel change prep procedure (described in Table V-3, 

step 5). These checks involve bringing the vehicle up to 70 mph on the dynamometer and 

recording the time it takes to coast down to 30 mph while in neutral. This provides a screen for 

friction or miscalibration issues that can affect program results. If a difference was found of 

more than 0.5 s between two back-to-back checks, or more than 7 s from a running average, the 

results were flagged for follow-up investigation. These values were chosen based on criteria 

used for quality control in certification testing. While there were occasional deviations noted, no 

significant, reproducible issues were found with coastdown times. 

 1. Emission Measurements

 The LA92 test cycle used in this program was broken into three portions, or bags, as 

shown in Figure V-2. The bag-level emissions measured and reported in all bags and replicates 

were THC, NMHC (by FID), NOX, NO2, CO, CO2, and particulate mass. In addition to the 

dilute, bagged exhaust samples, continuous raw tailpipe exhaust mass emissions rates were 

measured on a second-by-second basis for all replicates for THC, CH4, CO, NOX, CO2 and O2. 

A subset of tests also had measurement of speciated alcohols, carbonyls, and hydrocarbons, as 

well as NMOG and NMHC values calculated to adjust for partial response of the test cell FID to 

oxygenated species. All tests and replicates also have reported composite values computed using 

A, 

lbs

B, 

lbs/mph

C 

lbs/mph2

A, 

lbs

B, 

lbs/mph

C 

lbs/mph2

2008 GM Chevrolet Cobalt CCOB 3,125 21.51 0.5409 0.01521 4.22 0.20100 0.017055 11.5

2008 GM Chevrolet Impala FFV CIMP 3,875 19.87 0.4397 0.01752 8.320 0.11210 0.018601 11.4

2008 GM Saturn Outlook SOUT 5,000 38.61 0.3921 0.02818 19.860 0.07430 0.030294 17.2

2008 GM Chevrolet C1500 Silverado FFV CSIL 5,500 28.80 0.8005 0.03219 18.130 0.31630 0.035662 19.9

2008 Toyota Toyota Corolla TCOR 2,875 22.10 0.1500 0.01886 8.080 -0.02580 0.020902 10.2

2008 Toyota Toyota Camry TCAM 3,625 29.16 0.1659 0.01844 10.110 -0.15630 0.019592 11.1

2008 Toyota Toyota Sienna TSIE 4,500 38.41 0.0249 0.02946 16.270 -0.12110 0.029718 15.1

2008 Ford Ford Focus FFOC 3,000 27.66 0.2892 0.01697 15.240 0.07660 0.018743 11.3

2008 Ford Ford Explorer FEXP 4,750 32.35 0.6076 0.02716 14.350 0.43360 0.028153 17.4

2008 Ford Ford F150 FFV F150 5,250 27.26 0.9495 0.02932 4.300 0.83540 0.029383 19.7

2008 Chrysler Dodge Caliber DCAL 3,500 52.75 -0.3153 0.02826 15.990 -0.20400 0.025692 14.4

2008 Chrysler Dodge Caravan FFV DCAR 4,750 35.94 0.6505 0.02155 18.470 0.30710 0.023981 16.3

2008 Chrysler Jeep Liberty JLIB 4,250 29.53 0.4040 0.02955 9.410 0.13330 0.031781 16.5

2008 Honda Honda Civic HCIV 3,000 23.18 0.1904 0.01699 8.120 0.05150 0.017724 10.0

2008 Honda Honda Odyssey HODY 4,750 28.70 0.6915 0.02167 11.170 0.24850 0.024710 15.7

2008 Nissan Nissan Altima NALT 3,500 47.47 -0.4531 0.02414 19.710 -0.30660 0.021358 11.4

ROAD 

LOAD HP 

@ 50 mph

ETW, 

lbs

TARGET COEFFICIENTS SET COEFFICIENTS

NAME MODEL 

YEAR MAKE BRAND MODEL
61 

FTP weighting factors (43% bag 1+2 plus 57% bag 2+3), primarily as a matter of convention as 

no parallel factors exist for weighting portions of the LA92.22 

Figure V-2. Speed vs. time schedule of California Unified Cycle (LA92). 

a. Methods 

 Gaseous emissions were determined in a manner consistent with EPA protocols for lightduty emission testing as given in the CFR, Title 40, Part 86. A constant volume sampler was 

used to collect proportional dilute exhaust in Kynar bags for analysis of carbon monoxide (CO), 

carbon dioxide (CO2), total hydrocarbons (THC), methane (CH4), and oxides of nitrogen (NOX). 

Dilution air flow entering the sampling system was measured with a smooth approach orifice, 

and a critical flow venturi measured bulkstream dilute exhaust flow. Measured dilution air flow 

 

22 EPA performs inventory modeling using modeling techniques that break emission rates down by individual 

operating modes. Therefore the application of fixed weighting factors to emission bags to create a single composite 

result representing average driving is primarily done for historical reasons. 

0

10

20

30

40

50

60

70

0 500 1000 1500 2000

Speed (mph)

Time (s)

Bag 1

600s 

1.2 mi

Bag 2

1135s 

8.3 mi

Soak

600s 

0 mi

Bag 3

300s

1.2 mi
62 

was subtracted from the bulkstream flow to calculate raw exhaust flow to determine continuous 

raw mass emission rates.23

During Phases 1 and 2 of the test program, continuous raw NH3 measurements were 

made. Results showed NH3 spikes of several hundred ppm during testing of many of the 

vehicles. These concentrations were sufficient to cause poisoning of the NO2-to-NO converter in 

the continuous raw NOX analyzer. In an attempt to minimize this problem, prior to the start of 

Phase 3 SwRI installed two NH3 adsorbers in series upstream of the continuous raw emission 

measurement sample train. These adsorbers were changed daily. Additionally, the NO2-to-NO 

converter was purged with 5,000-ppm (nominal) NOX for five minutes following every test in an 

effort to reverse any NH3 poisoning of the converter that may have occurred during testing. The 

NOX analyzer was then purged for another three minutes with zero nitrogen prior to initiating the 

normal pre-test zero-span sequence.

 For the measurement of PM (particulate matter) mass emissions, a proportional sample of 

dilute exhaust was drawn through Whatman Teflon membrane filters after secondary dilution 

with HEPA-filtered air. A single filter was used for each bag, with both clean and dirty filters 

being weighed three times after a period of stabilization in a temperature and humiditycontrolled clean room. Replicate weights were required to be within ±2 μg or the result was 

void. The PM sampling method was compliant to CFR, Title 40, Part 1065. Several parameters, 

such as filter face velocity and temperature and dilution ratio, were monitored and reported for 

each test. 

 Sampling and analysis of alcohols was done in a manner similar to CARB method 1001, 

“Determination of Alcohols in Automotive Source Samples by Gas Chromatography”. Dilute 

exhaust was bubbled through glass impingers containing deionized water. Immediately 

following the test, samples were sealed and stored below 40°F until analysis. Most samples were 

analyzed on the day they were collected, but no later than within six calendar days. 

 

23 An electronic flow measurement device (referred to as an EFM) was used to measure raw exhaust flow during 

Phase 1 of the program, and results were found to be sufficiently similar to the SAO subtraction method. Given this 

fact, as well as cost and maintenance issues related to the EFM, it was not used in Phase 3.
63 

 Sampling and analysis of carbonyl compounds was conducted in a manner similar to 

CARB method 1004, “Determination of Aldehyde and Ketone compounds in Automotive Source 

Samples by High Performance Liquid Chromatography”. Dilute exhaust was drawn through 

cartridges containing DNPH, a compound that selectively binds to carbonyl groups to form 

stable complexes with known properties. The DNPH media were extracted using acetonitrile 

within 15 minutes of collection, and the extracts sealed and stored immediately at a temperature 

below 40°F. Most of these extracts were analyzed on the day they were collected, but no later 

than within three calendar days. An effort was made to detect the presence of a tautomer of 

acrolein, acrolein-x, which can be a measurement artifact. No acrolein-x was found in any 

exhaust sample. Additionally, storage of alcohol and carbonyl samples was segregated to 

prevent any cross-contamination of samples. 

 During carbonyl speciation work in Phases 1-2 of the program, SwRI noticed that 

background levels of some species (e.g., acetone and acetaldehyde) were relatively high and/or 

shifted in time in ways that were suspicious. SwRI began tracking daily media blanks and found 

that new, unused cartridges contained background levels of some species that were similar to the 

levels found in dilute exhaust. Thus, a protocol was developed for determining limits of 

quantitation (LOQs) of results based on media blank levels. These LOQs were determined for 

each compound on each test day using recent blank measurements. A detailed description of this 

process is given in Appendix L. 

 Sampling and analysis of C2-C12 hydrocarbons was conducted in a manner similar to 

CARB method 1002/1003, “Procedure for the Determination of C2-C12 Hydrocarbons in 

Automotive Exhaust Samples by Gas Chromatography”. During the analysis of C2 - C4

hydrocarbons, special consideration was given to 1,3-butadiene. Because of the instability of 

1,3-butadiene, the analysis of C2 - C4 hydrocarbon samples collected during Bag 1 of a test cycle 

was initiated within one hour of collection. The speciation of C5 - C12 hydrocarbon samples 

collected in Bag 1 of the test cycle was completed within 4 hours of collection. 

The following daily sequence was used for the analysis of VOC samples:
64 

• VOC samples collected during Bag 1 of the test cycle were analyzed first, in the 

sequence of vehicle tests.

• If a vehicle requiring VOC sampling during all three bags of the test cycle was tested, 

the Bag 1 was analyzed first, followed immediately by the Bag 3 sample and finally 

by the Bag 2 sample.

• Background samples were analyzed last, in the sequence of vehicle tests.

A summary of measurement methods is shown in Table V-5. Additional details on 

measurement equipment and related QA procedures are given in Appendix K. 

Table V-5. Exhaust emission measurement methods. 

Constituent Analysis Method

Total hydrocarbon Heated flame ionization detector (bag, modal)

Methane Gas chromatography (bag, modal)

Carbon monoxide Non-dispersive infrared analysis (bag, modal)

Carbon dioxide Non-dispersive infrared analysis (bag, modal)

Oxides of nitrogen Chemiluminescence analysis (bag, modal)

Nitric oxide Chemiluminescence analysis (bag only)

Oxygen Magnetopneumatic detector (modal only)

Particulate matter Part 1065 gravimetric measurement (bag only)

Non-methane hydrocarbons Calculated from THC and CH4 (bag, modal)

Non-methane organic gases Calculated as specified in section VI.B (bag only)

Nitrogen dioxide Calculated from difference of NOx and NO (bag only)

C1 – C12 HC speciation Gas chromatography (bag only)

Alcohols Gas chromatography (bag only)

Carbonyls Liquid chromatography (bag only)
65 

 b. Schedule of Speciated Emission Measurements 

 Speciated volatile organic compounds (VOCs) measured in this program included C1 - 

C12 hydrocarbons, light alcohols, and carbonyls (aldehydes and ketones). Due to the additional 

time and expense required, the scope of speciation covered a subset of vehicles and fuels. 

Alcohols and carbonyls were speciated during bag 1 for all tests (vehicles, fuels, replicates). C1 - 

C12 hydrocarbons were speciated for the first replicate on all vehicles for a subset of twelve fuels 

(3, 4, 6, 7, 10, 13, 14, 21, 23, 27, 28, and 31) chosen to provide, as nearly as possible, useful 

comparisons between different levels of ethanol, aromatics, T50, and T90. In addition, all types 

of speciation were carried out for bags 2-3 for the subset of 12 fuels on a subset of five vehicles 

(Civic, Corolla, F150, Impala, Silverado) intended to represent the range of sizes and 

technologies present in the larger test fleet. This information is summarized in Tables V-6 and 

V-7. All types of speciation were also carried out for all bags of all E85 tests (fuel 29). 

Table V-6. Speciation schedule by fuel, vehicle, and bag (excluding E85 tests). 

Vehicle Speciation Type Replicate 1 Replicate 2+

Bag 1 Bags 2-3 Bag 1 Bags 2-3 

CIMP, CSIL, 

F150, HCIV, 

TCOR

Alcohols, 

Carbonyls All fuels Subset shown in 

Table V-7 All fuels - 

Hydrocarbons Subset shown in 

Table V-7 

Subset shown in 

Table V-7 - - 

All others

Alcohols, 

Carbonyls All fuels - All fuels - 

Hydrocarbons Subset shown in 

Table V-7 - - - 

 
66 

Table V-7. Summary of fuel properties for speciation subset (excluding E85 tests). 

Fuel Ethanol T50 T90 DVPE Aromatics

 vol% °F °F psi vol%

3 10.4 218 296 6.9 15.0

4 9.9 222 338 10.0 15.5

6 10.6 189 340 7.2 15.0

7 <0.10 193 298 7.2 17.0

10 9.8 217 340 7.1 34.0

13 <0.10 223 338 6.9 34.1

14 <0.10 193 339 7.1 16.9

21 20.1 168 305 7.1 35.5

23 20.3 163 338 6.8 15.9

27 14.9 222 340 7.0 14.9

28 15.0 217 299 6.9 34.5

31 20.1 167 325 7.0 35.5

 2. OBD Data Collection 

Onboard diagnostic (OBD) system data were acquired at 1 Hz from each vehicle during 

all emissions tests using a DBK70 data acquisition system. On rare occasions, OBD data 

collection failed during a test; this was not grounds for repeating a test. This dataset includes the 

following parameters:

• Engine RPM 

• Vehicle speed

• Engine load 

• Short term fuel trim-bank 1 

• Long term fuel trim-bank 1 

• MIL status

• Absolute throttle position

• Engine coolant temperature 

• Short term fuel trim-bank 2 

• Long term fuel trim-bank 2 

• Fuel/air commanded equivalence ratio
67 

• Alcohol fuel percent (if available)

• Manifold absolute pressure 

• Spark advance 

• Engine control module voltage

• Air flow rate from mass air flow sensor

 3. Data Quality Control 

a. SwRI Procedures 

 A number of automated data quality checks were used by SwRI during collection and 

processing of data. The individual test files contain a QA tab showing a number of quantitative 

checks including: zero/span results for emission analyzers; PM filter weight gains, face 

velocities, and temperatures; bag-modal emission mass agreement; status of OBD channels on 

the vehicle CAN bus; test cell humidity. The test log file shows the status of additional checks 

such as repeatability ratio for requirement of a third replicate, long crank time flag, and pass/fail 

for chemistry and PM analyses. 

 b. EPA Procedures 

 Typically within about one week of completion of a test, SwRI would place the data file 

on a secure FTP site for review by the program sponsors. On approximately a weekly basis, 

EPA staff loaded the new data files into a database and ran various queries to look for other 

potential data quality anomalies. Any questions or issues were then raised during the weekly 

conference call with SwRI and other involved parties. 

E. Drift Check Tests 

Measurements may be affected by any of a variety of sources of drift, generally 

understood to be a systematic or progressive shift in results due to vehicle wear, instrumentation 

calibration changes, fuel weathering over time, etc. A rigorous scheme for detecting drift in a 
68 

test program such as this one would involve a large amount of redundant testing, for instance 

adding replicates for each vehicle/fuel combination at several points throughout the program. 

Needless to say, this would have increased cost and effort significantly, and did not seem 

justified given the quality control procedures already in place to minimize variability, as well as 

the fact that vehicle/fuel combinations were being tested in a randomized sequence. 

Nonetheless, as a screen for any gross drift that might affect the program results, each vehicle 

was re-run on a fuel from early in its sequence again at the mid-point and end. 

 

 Due to concerns with vehicles properly adapting to different ethanol contents in the test 

fuels, the following drift check procedure was conducted. To ensure that the test vehicles were 

similarly adapted during start-, mid-, and end-point testing, the test matrix was manipulated so 

the immediate history prior to mid- and end-point vehicle testing was substantially similar to that 

at the beginning of Phase 3. Specifically, all vehicles were operated on two successive E0 fuels 

for the first three weeks of testing, which had been immediately preceded by operation on an E20 

fuel at the end of Phase 2 of the program. The second E0 fuel for each vehicle was designated as 

the drift check fuel. With the assistance of EPA, SwRI scheduled mid- and end-point testing to 

be immediately preceded by an E20 or E15 fuel and then an E0 fuel with properties substantially 

similar to the first Phase 3 fuel on which each vehicle was tested.

 Due to the scheduling of end-point drift checks, five of the original ten vehicles 

completed testing during Week 34, while the remainder of the original ten vehicles completed 

testing during Week 37. (The Ford Explorer did not complete end-point testing until much later 

in the program due to a MIL issue described in Section V.F.2.) 

Various statistical analyses were conducted, including graphical assessment of emission 

trends, modeling measurements as a function of odometer reading, and modeling measurements 

as a function of the time of test (beginning, middle, end). 

No consistent drift in time-of-test measurements was found. For example, in 120 

pairwise comparisons of beginning, middle and end measurements (10 measurements × 4 phases 

× 3 pairwise tests) using Tukey multiple-comparison-adjusted p-values, only one comparison 
69 

was found to be statistically significant: bag 1 CH4 means between beginning and end test runs. 

This sole significant result could easily have occurred by chance. Therefore, drift in emission 

behavior did not appear to occur in the test program. 

F. Issues encountered with Specific Vehicles

 1. Ford Explorer Oil Issues 

 An incorrect oil viscosity was used in the Ford Explorer during break-in. Ford specifies 

5W-30 grade for the 4.0L V-6 engine and 5W-20 for the 4.6L V-8. The test vehicle was 

equipped with the 4.0L V-6, and was incorrectly filled with the 5W-20 oil at both the start of 

mileage accumulation and at the 2,000-mile oil change. The vehicle had accumulated 4,000 

miles when this error was discovered. After discussing this situation with all involved parties, 

the vehicle received a single flush with 5W-30 oil (2 drains and 2 fills with oil filter changes) and 

an additional 2,000 miles were accumulated on the Ford Explorer to break-in the correct oil.

 There also appeared to be an oil level issue with the Explorer. When the oil sample was 

collected following testing of the 15th fuel, the technician noticed that the oil level was below 

the minimum oil level on the dip stick. Following extensive discussions with all sponsors, an 

additional 20 ounces of fresh crankcase lubricant were added to the Ford Explorer before 

resuming testing. Details of this incident are given in Appendix M. 

As a result of this situation, starting in the 22nd week of Phase 3, the oil level on all 

vehicles was checked monthly. These checks were taken on a level floor inside the emissions 

lab following a minimum 12-hour soak at room temperature (72°F ± 2°F). Initial results showed 

the Toyota Camry oil level was between 1/4 and 1/8 of the distance from the fill level to the full 

level on the dipstick. The oil level of this vehicle was monitored weekly, but did not change 

during the rest of the program. No other vehicles had oil level issues. 

 2. Fuel System Evaporative Leak Check Failures (Explorer) 
70 

 During the 27th week of testing, the Ford Explorer illuminated a malfunction indicator 

light (MIL – a.k.a. “check engine light”) for diagnostic trouble code (DTC) P0455-Evaporative 

Emission System Leak Detected (Gross Leak/No flow). This started a series of troubleshooting 

events that are summarized in Table V-7. On-road testing seemed to indicate that code was not 

due to the fuel change procedure or operation of the vehicle on the chassis dynamometer. 

Following extensive discussions that included input from Ford technical staff, the team decided 

that the MIL would not have an adverse affect on emissions testing, and the vehicle was placed 

back into the test matrix.
71 

Table V-7. Troubleshooting of the Ford Explorer evaporative system MIL

DATE ACTION

9/16/2009 Fuel change to E20 Fuel 31; key off

9/17/2009 MIL light during vehicle conditioning, E20 Fuel 31; PO455-Evaporative Emission System Leak 

Detected (Gross Leak/ No Flow)

9/23/2009 Vehicle sent to dealer; performed a smoke test; Canister vent solenoid replaced

9/26/2009 Fuel change to E20 Fuel 21; key off

9/27/2009 MIL light during vehicle conditioning, E20 Fuel 21; PO455-Evaporative Emission System Leak 

Detected (Gross Leak/ No Flow)

10/5/2009 Vehicle sent to dealer; performed a smoke test; capless fuel filler door was cleaned as it had dirt and 

grime

10/12/2009 Fuel change to E20 Fuel 21; key off

10/13/2009 MIL light during vehicle conditioning, E10 Fuel 12; PO455-Evaporative Emission System Leak 

Detected (Gross Leak/ No Flow)

10/16/2009 SwRI performed an IDS test and a smoke test and a leak test by pressurizing the evap system and 

found no leaks.

10/26/2009

FEXP was taken to the test track where we ran 9 WOT up to 70 mph. The MIL did not light. The next 

day we ran through the three LA 92 (2-bag) prep sequence on the dyno. The MIL did light 

approximately 500 seconds (~24 miles) into the third LA 92. This means the fuel change procedure is 

probably not the cause for the MIL. 

10/28/2009 Vehicle was driven on road approximately 50 miles. Pending code P0422, but no MIL light

11/20/2009

Vehicle sent to the dealer; The EVAP system was smoke tested and the capless fuel assembly was 

replaced. I was told that the technician drove the vehicle for more than 10 miles to confirm that the 

code did not reappear.

11/21/2009 Fuel change to E15 Fuel 28; key off

11/22/2009 MIL light during vehicle conditioning, E15 Fuel 28; PO455-Evaporative Emission System Leak 

Detected (Gross Leak/ No Flow)

12/1/2009 Dealership performed IDS Diagnosis, PO455 code. EVAP test found capless retainer broken. 

Replaced retainer and retested ok.

12/8/2009 MIL light during vehicle conditioning, E15 Fuel 28; PO455-Evaporative Emission System Leak 

Detected (Gross Leak/ No Flow)

 

 Following Phase 3 testing, SwRI performed additional evaporative system leak checks 

with an IDS scan tool per instructions given by Ford technical staff, and the data files were 

forwarded to Ford for review. Subsequent coordination among SwRI, Ford technical staff, and 

the local Ford dealership allowed us to determine that the fuel tank pressure sensor had an 

internal fault causing the signal to become erratic during vehicle operation, after which the 

vehicle was repaired.
72 

 3. Transmission Module Malfunction (Outlook) 

 A MIL illuminated during the second test of Fuel 16 with the Saturn Outlook. The codes 

found were Tran Control Sys Malfunction and U0073 - Control Module Comm. Bus Off. The 

MIL and same codes had occurred previously while operating the vehicle on the mileage 

accumulation dynamometer during the initial vehicle break-in. At that time, the vehicle was 

taken to the dealership where the codes were cleared, and the MIL did not recur until testing Fuel 

16. 

 Review of the emissions results from the two tests on Fuel 16 did not show a significant 

difference. With EPA’s and NREL’s approval, the codes were cleared and the vehicle was 

placed back into the test program. Four days later, the MIL came on again during testing, with 

the same DTCs. This time the driver noticed that the vehicle’s engine was revving higher than 

usual at cruising speeds and shifting hard during the first two bags. Bag 3 did not have the same 

issues. With EPA’s and NREL’s approval, the vehicle was taken to the dealer for diagnosis, but 

they were not able to find any problems. There was concern that the DBK system used to collect 

OBD data may have somehow been interfering with proper vehicle operation. The next set of 

tests was conducted without OBD data acquisition, and the MIL did not illuminate. All 

subsequent tests were conducted without OBD data acquisition, and the MIL did not illuminate. 
73 

VI. DATA REPORTING

A. Products and Formats

 This program generated a large amount of primary data covering fuels, emissions, and 

test conditions, available as follows: 

• Individual test files (956 Microsoft Excel files, 3.6 MB each)

• Phase 3 testing log file (1 Microsoft Excel file, 845 KB) 

• Phase 3 E85 testing log file (1 Microsoft Excel file, 37 KB) 

• Test vehicle fleet data file (1 Microsoft Excel file, 46 KB) 

• Fuel property data file with round robin results (1 Microsoft Excel file, 58 KB) 

• Fuel speciation results (28 PDF files, 270 KB each) 

Summary database files are also available covering gaseous, PM and speciation results. 

 1. Overview of Individual Test File Contents 

The individual test files were produced in Microsoft Excel 2003 format, and use a 

standardized layout of six tabs with consistent row/column locations of particular data fields 

across all files. A summary of the contents of the six spreadsheet tabs is as follows: 

Output-BagSummary 

• Pretest data: date, time, test number, vehicle and fuel identification

• Test conditions: phase times, distances, test cell temp, humidity, crank times

• Emission results: concentration and g/mi results by bag and weighted for all pollutants 

Output-QA

• Data and process quality checks, including: bag-to-modal comparison, PM collection 

parameters, analyzer zero/span check results, OBD CAN data channel status by 

parameter, test cell humidity time in-spec, average power and work by bag 
74 

Output-UnregSummary 

• Summary of min/max/average by phase of modal data for various species and pollutants 

• Note: This tab was assembled during Phase 1 when additional modal speciation was 

being done; for Phase 3 only “TP Raw” results are valid here (others may contain zeros 

or other values that are not necessarily accurate).

Output-ModalData 

• Second-by-second measurements of OBD and CVS parameters, tailpipe raw 

concentrations, computed mass emission rates and cumulative totals 

 

Chemistry Summary 

• Mass and concentration data for alcohol, carbonyl, and gaseous hydrocarbon data, as 

available for a given test, after filtration by LOQs

• Limits of quantification (LOQs) applied to speciation data 

• Concentration results for the subset of compounds being used to calculate NMOG results, 

after filtration according to LOQs

DataProcessingNotes 

• File review status

• FID response factors used in NMOG calculations 

• Miscellaneous notes on procedure and calculations 

 2. Treatment of Zeros and Missing Values

Speciation results in the Chemistry Summary sheet that were reported as zero after falling 

below the LOQ are denoted as “-99”. In other sheets, non-detects are simply reported as a 

numerical zero value. Missing data omitted for some reason other than a non-detect, such as due 

a voided sample, are indicated with the period character (“.”).

B. Calculation of NMOG and NMHC
75 

NMOG (non-methane organic gases) is defined as the sum of all organic emission 

species minus methane. It can be compared to NMHC (typically defined as FID THC minus 

methane), which contains an incomplete accounting of oxygenated emission species like 

formaldehyde, acetaldehyde, and ethanol due to the way the hydrocarbon analyzer operates.

24 

NMOG results can be generated either by fully speciating the exhaust and summing the masses 

of all compounds, or by starting with a FID-based NMHC result and then correcting it using 

speciation results for alcohols and carbonyls. A non-oxygenated NMHC total can be generated 

in the same way. Where alcohol and carbonyl speciation results were present (bag 1 in nearly all 

tests, and bags 2-3 in a subset per Table V-6), SwRI generated NMOG and non-oxygenated 

NMHC results based on corrected FID measurements as described in detail in Appendix N. For 

tests where there was no speciation, the calculation was performed assuming oxygenated species 

masses were zero, effectively setting the NMOG and NMHC values equal to the traditional 

NMHC definition of FID THC minus methane. 

 

24 See Appendix P for details on FID response to oxygenated compounds.
76 

VII. SUMMARY AND CLOSING REMARKS

This program collected regulated and unregulated emission data, by bag and second-bysecond, for 15 new, properly-operating light duty vehicles of 2008 model year using a 

statistically-designed partial factorial matrix of 27 gasoline test fuels covering typical market 

ranges of ethanol, T50, T90, aromatics, and RVP. Complete data were generated for 926 tests, 

with 30 additional tests containing valid measurements for most emissions. 

 During the execution of this program a number of questions about best practices for 

emission studies were raised, and experiments were carried out to answer some of them. 

Observations include: 

• New vehicles contain sophisticated engine control systems that can have significant 

effects on emission behavior. Specific fuel change and prep procedures must be followed 

to isolate to the greatest extent possible the impacts of fuel changes from transient 

behaviors resulting from learning processes occurring in engine controls. 

• Vehicle fuel tanks vary widely in how much fuel remains after being drained by the fuel 

pump, which can result in fuel carryover and increased variability of actual in-tank fuel 

properties during testing. Careful fuel change procedures can accommodate this. 

• As vehicle emission levels get lower and lower, more care must be taken to reduce 

sources of measurement error and variability. Speciation of carbonyls was one area 

found to be especially subject to this issue since DNPH cartridges contain background 

levels for some species of interest similar in magnitude to dilute emission levels. In 

addition, dilute gaseous emission measurements such as NOx may have sample 

concentrations similar in magnitude to background for some portions of the test (e.g., 

bags 2-3).