UNITED STATES ENVIRONMENTAL PROTECTION AGENCY NATIONAL VEHICLE AND FUEL EMISSIONS LABORATORY 2565 PLYMOUTH ROAD ANN ARBOR, MICHIGAN 48105-2498

OFFICEOF AIR AND RADIATION July 21, 2005 CCD-05-12 (LDVILDT/MDPV/HDV/HDEILD-AFC)
DearManufacturer: Subject: Clean-Fuel Vehicle Standards This letterprovides guidance on determining the equivalency ofvehicle andengine emission standards in Code ofFederal Regulations (CPR) Part 86 standards andPart 88 standards for Clean-Fuel Vehicles. The determinations that follow may be used effective with the issue date ofthis guidance letter. Background The EPA Clean-Fuel Fleet Program (CFFP) was establishedby the requirements under Part C- Clean-Fuel Vehicles, Sections 241-246 ofthe1990 Clean Air Act (CAA) Amendments. The purpose ofthe CFFP was to reduce emissions in metropolitan areas notmeeting Federal air quality standards through the use ofclean alternative fuels. 1 The CAA prescribedexhaust emission standards for light-duty vehicles, light-duty trucks, and heavy-duty vehicles between 8,501lbs and 26,000 lbs GVWR?
In response to the Clean-Fuel Vehicle (CFV) requirements ofthe CAA Amendments, EPApublishedregulations in 40 CPRPart 88, Subpart A, Emission Standards for CleanFuel Vehicles, and Subpart C, Clean-Fuel Fleet Program. Following the requirements in Sections 242, 243, and 245 ofthe CAA Amendments, EPA published standards for three vehicle classes: light-duty vehicles (LDVs), light-duty trucks (LDTs) up to 8,500 lbs GVWR, andheavy-duty vehicles (HDVs) between 8,501lbs and 26,000 lbs GVW. A CFV light-duty vehicle or light-duty truck can be classified as a transitionally low emissions vehicle (TLEV), low-emission vehicle (LEV), ultra low-emission vehicle (ULEV), ora zero emission vehicle (ZEV). Heavy-duty vehicles orengines used in heavy-duty vehicles are classified as low-emission vehicle (LEV), ultra low-emission vehicle (ULEV), inherently low-emission vehicle (ILEV) or a zero emission vehicle (ZEV). Subsequent to publishingits CFVregulations, EPA has promulgated new emission standards that are generallymore stringent than orequivalent to the CFV emission

1Section 241(2) ofthe 1990CAA Amendments lists the following fuel types as clean alternative fuels: any fuel mixture with gasoline orother fuel containing 85% ormore (by volume) methanol, ethanol, or other alcohol, reformulated gasoline, diesel, natural gas, liquefiedpetroleum gas, hydrogen, and electricity. 2 Section 241(7) defines a clean-fuel vehicle as"

.... a vehicle in a class orcategory ofvehicles which has been certified to meet for any model year the clean-fuel vehicle standards applicable under this part for that model year to clean-fuel vehicles in that class orcategory."

1 

## @ Printed on Recycled Paperstandards for light-duty vehicles, light-duty trucks, andheavy-duty engines. These new EPA regulations added a new medium-duty vehicle passengerclass, and also created a new chassis test procedure for heavy-duty vehicles.
Vehicle and engine manufacturers continue toreceive requests from fleet customers who desire to purchase vehicles compliant with CFV standards.3 Manufacturers have requestedEPA guidance on how to continue to demonstrate to fleet customers that current standards are equivalentto ormore stringent than CFV standards.
The CFV emission standards for vehicles and engines are presentedin 40CFRPart 88 Subpart A, sections 88.104-94 for vehicles and in 88.105-94for heavy-duty engines. Current federal vehicle and engine certification emission standards are publishedin 40 CFR Part 86. Specifically, light-duty vehicle, light-duty truck, and medium-duty passenger vehicle standards are presented in 86.1811-04 and completeheavy-duty vehicle emission standards are presentedin 86.1816-05 and 86.1816-08. Otto cycle standards for the 2005-2007 model yearheavy-duty engines and vehicles are presentedin 86.005-10 and in 86-008-10for 2008 and latermodel years. Diesel cycle emission standards for 2004-2006 model yearheavy-duty engines and vehicles are presentedin 86.004-11 and in 86.007-11 for 2007 and latermodel years. Determination To determine equivalency, current certification emission standards for Tier2 vehicles (LDVs, LDTs, and MDPVs), heavy-duty vehicles, heavy duty Otto cycle engines, and heavy-duty diesel engines were compared to CFV vehicle and engine emission standards using the methodology outlinedin the Attachment. The results ofthis analysis are summarized as follows:
Tier 2 LDVs, LDT1-4s, andMDPVs certified to the following Tier 2 bin standards are equivalent to ormore stringent than CFVLEV emission standards:
LDV Bins 1-7 andBin 9 LDT1 Bins 1-7 and Bin 9 LDT2 Bins 1-9 LDT3 Bin 1-10 LDT4 Bin 1-10 MDPV Bin 1-11 4
Tier 2 LDVs, LDT1-4s, andMDPVs certified to the following bin standards are equivalent to ormore stringent than CFVULEV emission standards:
LDV Bins 1-3 LDTl Bins 1-3 LDT2 Bins 1-4

3Correspondence addressed toEPA from theEngine Manufacturers Association dated December 8, 2004. 4There are no CFV emission standards thatcorrespond to the Tier 2MDPV class butMDPVs meetingTier 2 Bins 1-ll are all equal to or more stringentthanLDT4 CFVLEV standards.

2LDT1 Bins 1-3 LDT2 Bins 1-4 LDT3 Bins 1-4 LDT4 Bins 1-4 MDPV Bins 1-45
The following determinations are made for 2005 and latermodel year Otto cycle heavyduty vehicles: 8,501-10,000 GVWR Otto-cycle heavy-duty vehicle chassis standards are more stringentthan the CFV Otto cycle heavy-duty engine LEV emission standard. 10,001-14,000 GVWR Otto-cycle heavy-duty vehicle chassis standards are more stringent than the CFV Otto cycle heavy-duty engine LEV emission standard.
The following determinations are made for 2005 and later model yearheavy-duty Otto cycle engines and diesel engines:
Current emission standards for heavy-dutyengine Otto cycle engines and diesel engines are more stringent than CFV LEV heavy-duty Otto cycle engines, or heavy-duty diesel engine emission standards. Compliance with EPA Standards and Program Requirements Manufacturers may assure fleet managers that vehicles and engines certifiedunder current emission standards which EPA has determinedto be as ormore stringent than corresponding CFV emission standards meet CFV emission standards. (See the Determination section above for determining which current standards qualify) Section 40CFR 86.1817-0S(a)(l) prohibits heavy-duty vehicles and engines labeled for use in clean-fuel vehicles from participating in EPA's NOx averaging, banking, and trading (ABT) program. Similarly, 40 CFR 86.004-15(a)(l) also prohibits CFV-labeled engines in heavy-duty engine families from participating in NMHC plus NOx, and particulate ABT. Engines that are not labeled CFV-compliant are eligible to participate in Part 86 ABT programs. This guidance document shows which Part 86 emission standards are equivalent to or more stringent than CFV emission standards. This document does not change any ofthe requirements ofthe CFFPin Part 88. Manufacturers certifying underPart 88 CFFP emission standards are not exempt from complying with all otherCFFPrequirements. Questions concerning CFV standards and CFFP requirements for vehicles up to 14,000 GVWR vehicles may be directed to Martin Reineman, 734-214-4430, or reineman.martin@epa.gov. Questions on CFV engine standards and CFFP requirements maybe directedto Jason Gumbs, 202-343-9271, orgumbs.jason@epa.gov.

5There are no CFV standards that correspond to the Tier 2MDPV class butMDPVs meetingTier2 Bins 1- 4 are all equal to or more stringentthanLDT4 CFV ULEV emission standards.
3Attachment Sincerely,

# ~~~ Merrylin Zaw-Mon, Director Certification and ComplianceDivision Office ofTransportation and Air Quality

4Attachmentto CCD-05-12 

### Analysis ofCFVEmission Standards
There are four issues which must be addressed in orderto determine the equivalency of CFV standards and the federal certification emission standards: determining CFVequivalent standards for the newly-addedMDPV class, equating grams perbrake horsepower-hour standards and grams permile standards, converting NMHC to NMOG, and determining equivalency for a combinedNMHC+NOx CFV standard when current federal standards are expressed as separate NMHC and NOx standards.
1. How to address the newly-added vehicle class ofMedium-Duty PassengerVehicle (MDPV). The newly-addedclass ofMedium-Duty Passenger Vehicles (MDPVs) did not exist at the time ofthe CFV regulations. These vehicles include heavy-duty vehicles weighing less than 10,000pounds GVWR designed primarily for carrying passengers. These vehicles would have been considered as heavy-duty vehicles under the CFV provisions. However, they would not have been testedin the same way- MDPVs are chassis-tested, whereas heavy-duty vehicles were engine-tested. The issue that arises from this is that the engine testing-based emission standards are expressed in different units than chassis testing-based standards, as discussedbelow.
2. Converting glbhp-hrinto g/mi. The CFV standards for heavy-duty vehicles (which, at the time were tested on engine dynamometers) are expressedin units ofglbhp-hr. The CFV standards for light-duty vehicles (tested on chassis dynamometers) are expressed in grams permile. Since the time ofthese standards, some heavy-duty vehicles are now required to be tested on chassis dynamometers. Also, the new class ofMDPVs has g/mi standards, whereas under the CFV program, they wouldhave had glbhp-hr standards. To determine ifCFV emission standards for these vehicles are equivalentto ormore stringent than the federal certification emission standards in effect today the glbhp-hr standards must be converted into g/mi.
Forengine standards in the 8,501-10,000 GVWR range (such as MDPVs), the glbhp-hr units are converted to g/mi units by multiplying themby the factor 1.096. Forengine standards in the 10,001-14,000 GVWR range, convert glbhp-hrunits to g/mi units by the factor 1.150. The CFV glbhp-hrengine emission standards for vehicles between 8,500 and 14,000 GVWR were converted to g/mi units by using EPA-derived conversion factors contained in EPA Report No. EPA420-R-00-010. 1 The 1.096 and 1.150 conversion factors referencedin this guidance letter are used solely for the purpose of equatingPart 86 chassis test and Part 88 engine test standards for vehicles in the 8,501- 14,000 GVWrange. Accurate assessment ofemissions from a unique vehicle/engine configuration can only be accomplished by conducting dual emissions measurements using both chassis test and engine test procedures and protocols.

1This report is available on-line at www.epa.gov/otaq/regs/hd-hwy/2000frrnlr00010.pdf

13. ConvertingNMHC intoNMOG. CurrentTier 2 vehicle emission standards for hydrocarbons are presented as non-methane organic gas (NMOG); whereas CFV engine emission hydrocarbon standards are based on non-methane hydrocarbons (NMHC). NMOG may be converted to NMHC by use ofthe equation: NMOGemissions=NMHC*1.04 The 1.04 factor was published as part ofEPA's Tier 2regulations.
4. Combinedemission standards. The CFV standards for heavy-duty vehicles include acombinedNMHC+NOx standard expressed in glbhp-hr. To compare to today's standards, not onlymust the measurement units be converted, but the NMHC standard must be converted to NMOG. Also, because the Tier 2 standards do not include a combined standard, it is necessary to add the chassis-based NMOG standard and the chassis-basedNOx standard, after using the appropriate g/mi to glbhp-hrconversion factor.
Forexample, to compare the 2005-2007 model yearheavy-duty vehicle chassis-based standards for NMOG (0.28 g/mi) and NOx (0.9 g/mi) to the corresponding CFV engine basedemission standard for the sum ofNMHC + NOx (3.8 glbhp-hr), thefollowing conversions were performed: Converting 0.28 g/mi NMOGto NMHC: 0.280 g/mi NMOG/1.04 

### =0.27 g/mi NMHC Summingthe 0.27 g/mi NMHC and 0.9 NOx heavy-duty vehicle chassis standards: 0.27 g/mi NMHC + 0.9 g/mi NOx = 1.17 g/mi (NMHC + NOx) Converting the 3.8 glbhp-hrCFV engine based standard to g/mi units: 3.8 glbhp-hr (NMHC + NOx)*1.096 = 4.16 g/mi (NMHC + NOx) Comparing the current heavy-duty vehicle chassis standard to the CFV engine standard: 1.17 g/mi <4.16 g/mi

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