APPENDIX B

SUMMARY OF THE CALIFORNIA AND FEDERAL

LIGHT- AND MEDIUM-DUTY VEHICLE PROGRAMS
1

APPENDIX B

SUMMARY OF THE CALIFORNIA LEV II AND FEDERAL TIER 2 PROGRAMS TO

CONTROL EMISSIONS FROM LIGHT- AND MEDIUM-DUTY VEHICLES

I. The California LEV II Program

A. The Original California Low-Emission Vehicle (LEV I) Program

In September 1990, the Air Resources Board (ARB or Board) adopted the original

California Low-Emission Vehicle (LEV I) regulations, requiring automobile manufacturers to

introduce progressively cleaner light- and medium-duty vehicles with more durable emission

controls from 1994 through 2003. The LEV program is California’s long-term plan to achieve

the greatest possible emission reductions in the most efficient manner. The LEV I regulations

provided manufacturers with the stability needed to optimize resources for accomplishing

product changes and advance notice for them to invest in developing advanced vehicle

technologies to meet California’s clean air goals.

The LEV I regulations included three primary elements:

(1) Tiers of exhaust emission standards for increasingly stringent categories of lowemission vehicles;

(2) A mechanism requiring each manufacturer to phase-in a progressively cleaner mix of

vehicles from year to year with the option of credit trading; and

(3) A requirement that a specified percentage of passenger cars and lighter light-duty

trucks be ZEVs, vehicles with no emissions. Since the current rulemaking does not

affect the ZEV requirements, a very abbreviated discussion of ZEVs is provided.

1. The LEV I Exhaust Emission Standards

The LEV I program established four low-emission vehicle categories to which a

passenger car or lighter light-duty truck could be certified: Transitional Low-Emission Vehicle

(TLEV), Low-Emission Vehicle (LEV), Ultra Low-Emission Vehicle (ULEV) and ZEV. For

medium-duty vehicles, there are four categories: LEV, ULEV, Super Ultra Low-Emission

Vehicle (SULEV) and ZEV. Light- and medium-duty vehicles could also be certified to the

preexisting exhaust emissions standards, which were called the “Tier 1” standards.

Each low-emission vehicle category has had a progressively more stringent standard for

exhaust emissions of nonmethane organic gas (NMOG), a precursor of ozone pollution in the

lower atmosphere. For example, a passenger car TLEV has had to meet an NMOG emission

standard that is about one-half of the corresponding basic standard for 1994 model vehicles.

Passenger car LEVs and ULEVs have had to meet standards for NMOG that are respectively
2

about one-third and one-sixth of the corresponding 1994 standard. The identical LEV and

ULEV standard for oxides of nitrogen (NOx) has represented a 50% reduction from the basic

NOx standard for 1994 passenger cars, and the ULEV standard for carbon monoxide (CO) also

represents a reduction of about 50% from the basic 1994 CO standard.

All passenger cars were subject to the same low-emission vehicle standards, regardless of

weight. However, for light-duty trucks and medium-duty vehicles, the numerical standards for

each low-emission vehicle category depended on the weight classification of the vehicle.

As shown in Table 1, there were two weight categories (LDT1 and LDT2) for light-duty trucks,

which can have a gross vehicle weight (GVW) of up to 6,000 pounds. For medium-duty

vehicles, which have a GVW of 6,000-14,000 pounds, there were effectively four weight

categories: MDV2, MDV3, MDV4 and MDV5.

The lightest light trucks making up the LDT1 category, such as the Toyota RAV4 and

Ford Ranger, had to meet the same standards as passenger cars. The medium-light trucks in the

LDT2 category, such as the Jeep Grand Cherokee and essentially all mini-vans, were allowed to

emit about 25-33% more NMOG and CO, and 75-100% more NOx, than passenger cars in the

same low-emission vehicle categories. The MDV2 category included heavier vehicles such as

the Ford F150, which were subject to the same NOx standards as LDT2s, but could emit about

110-150% more NMOG than equivalent passenger cars. The MDV3 category included vehicles

such as the Dodge Ram 1500 truck, Ford Expedition and most Suburbans, which were subject to

LEV emission levels for NMOG and NOx that were 160% and 200% higher than those for

passenger cars. The MDV4 and MDV5 categories included vehicles such as the Ford Excursion,

the largest Suburban model, and the Dodge Ram 2500 and 3500 trucks.

The complete set of LEV I 50,000-mile emission standards to which vehicles could be

certified under the LEV I program is shown in Table 1. There are additional emission standards

at 100,000 miles for passenger cars and light-duty trucks and at 120,000 miles for medium-duty

vehicles. The 100,000 and 120,000 mile standards included standards for particulate from diesel

vehicles.

2. The LEV I Requirements for Phasing-in a Cleaner Vehicle Fleet

The LEV I regulations feature an increasingly stringent annual fleet average NMOG

emission requirement, which provides a flexible mechanism for phasing-in low-emission

vehicles. For each model year, an auto manufacturer may produce passenger cars and light-duty

trucks certified to any combination of emission levels – Tier 1, TLEV, LEV, ULEV, and SULEV

– as long as the NMOG fleet average requirement is met across the manufacturer’s full model

line. The required annual fleet average NMOG emissions levels, based on the 50,000-mile

NMOG standards, start at the Tier 1 level for the 1994 model year, and then become

incrementally more stringent through the 2003 model year. Table 2 shows the fleet average

NMOG requirements for passenger cars and light-duty trucks for each model year. The 2003

model-year level was derived from a potential vehicle mix of 75% LEVs, 15% ULEVs and 10%

ZEVs. The heavier light-duty trucks have been subject to numerically higher fleet average

NMOG emissions requirements reflecting the numerically higher TLEV, LEV and ULEV

standards and the absence of ZEV requirements.
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Table 1: The California LEV I Exhaust 50,000-Mile Emission Standards

Exhaust Mass Emission Standards for TLEV, LEV, and ULEV Passenger Cars and Light-Duty Trucks

and LEV, ULEV and SULEV Medium-Duty Vehicles

Vehicle Type Mileage for

Compliance

Vehicle

Emission

Category

NMOG

(g/mi)

Carbon

Monoxide

(g/mi)

Oxides of

Nitrogen

(g/mi)

Formaldehyde

(mg/mi)

Diesel

Particulate

(g/mi)

All PCs;

LDT1s (0-3750 lbs.

LVW)

50,000 Tier 1 0.25 3.4 0.4 n/a 0.08

TLEV 0.125 3.4 0.4 15 n/a

LEV 0.075 3.4 0.2 15 n/a

ULEV 0.040 1.7 0.2 8 n/a

LDT2s

(3751-5750 lbs. LVW)

50,000 Tier 1 0.32 4.4 0.7 n/a 0.08

TLEV 0.160 4.4 0.7 18 n/a

LEV 0.100 4.4 0.4 18 n/a

ULEV 0.050 2.2 0.4 9 n/a

MDV2s

(3751-5750 lbs. TW)

50,000 Tier 1 0.32 4.4 0.7 18 n/a

LEV 0.160 4.4 0.4 18 n/a

ULEV 0.100 4.4 0.4 9 n/a

SULEV 0.050 2.2 0.2 9 n/a

MDV3s (5751-8500 lbs.

TW)

50,000 Tier 1 0.39 5.0 1.1 22 n/a

LEV 0.195 5.0 0.6 22 n/a

ULEV 0.117 5.0 0.6 11 n/a

SULEV 0.059 2.5 0.3 6 n/a

MDV4s

8501 -10,000 lbs. TW

50,000 Tier 1 0.46 5.5 1.3 28 n/a

LEV 0.230 5.5 0.7 28 n/a

ULEV 0.138 5.5 0.7 14 n/a

SULEV 0.069 2.8 0.35 7 n/a

MDV5s

10,001-14,000 lbs. TW

50,000 Tier 1 0.60 7.0 2.0 36 n/a

LEV 0.300 7.0 1.0 36 n/a

ULEV 0.180 7.0 1.0 18 n/a

SULEV 0.09 3.5 0.5 9 n/a
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Table 2: Fleet Average NMOG Requirements

(gram/mile, based on 50,000-mile standards)

Vehicle Category 1994 1995 1996 1997 1998 1999 2000 2001 2002 2003+

PC and LDT1

(0-3750 LVW)

0.250 0.231 0.225 0.202 0.157 0.113 0.073 0.070 0.068 0.062

LDT2

(3751-5750 LVW)

0.320 0.295 0.287 0.260 0.205 0.150 0.099 0.098 0.095 0.093

Medium-duty vehicles have separate requirements based on a percent phase-in schedule,

because the numerous vehicle weight classifications and relatively low sales volumes make a

fleet average requirement approach more difficult to implement. Table 3 shows the phase-in

requirements for medium-duty vehicles. There are two types of MDVs – those that are certified

using the chassis dynamometer (the left column of Table 3) and those certified using an engine

dynamometer (the right column of Table 3). Chassis-certified vehicles make up about 80 percent

of the MDV category, and generally gasoline-powered. The remaining 20 percent of the MDV

category are engine-certified vehicles, mostly diesel-powered.

Table 3: Medium-Duty Vehicle Phase-In Requirements

Model

Year

Chassis Certified Vehicles

(% Sales)

Engine Certified Vehicles

(% Sales)

Tier 1 LEV ULEV Tier 1 LEV ULEV

1998 73 25 2 100 0 0

1999 48 50 2 100 0 0

2000 23 75 2 100 0 0

2001 0 80 20 100 0 0

2002 0 70 30 0 100 0

2003 0 60 40 0 100 0

2004 + 0 40 60 0 0 100

The regulations also establish a system for earning marketable credits for use in

complying with the phase-in requirements.

3. ZEV requirements

As originally adopted, the LEV regulations required that specified percentages of the

passenger cars and lightest light-duty trucks produced by each of the seven largest manufacturers

be ZEVs, starting in 1998. The percentages were 2% for the 1998-2000 model years and 5% for
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the 2001-2002 model years. A requirement of 10% ZEVs applied to all but small-volume

manufacturers starting in model-year 2003. In 1996 the Board eliminated the regulatory ZEV

requirements applicable prior to the 2003 model year. The ZEV element also includes a

marketable credits system.

B. The LEV II Program

The Low-Emission Vehicle II (LEV II) program, adopted following a November 1998

hearing, is an extension of the original LEV I program and is structured to provide additional

reductions needed to achieve California’s long term goal of healthful air quality by 2010.

The LEV II amendments include three major interrelated elements designed to reduce

exhaust emissions: (1) restructuring the light-duty truck category so that most SUVs, mini-vans

and pick-up trucks are subject to the same low-emission vehicle standards as passenger cars,

(2) strengthening the NOx standard for passenger car and light-duty truck LEVs and ULEVs, and

changing other emission standards, and (3) establishing more stringent 2004 and subsequent

model year phase-in requirements for passenger cars, light-duty trucks and medium-duty

vehicles. They also contain various other changes, including elimination of the TLEV standard

after the 2003 model year and a program for generating partial ZEV allowances.

1. Passenger car standards for light and medium trucks

Under the restructuring of vehicle weight classifications, all current light-duty trucks, and

all current medium-duty vehicles having a GVW of less than 8,500 lbs. – basically the MDV2

and MDV3 categories – will be subject to the same LEV and ULEV standards as passenger cars.

Only the very heaviest sport-utility vehicles (SUVs) and pick-up trucks in the MDV4 category

will remain subject to separate medium-duty vehicle standards, along with MDV5s. When the

vehicle categories were first established, the majority of vehicles in the LDT2 and medium-duty

categories were primarily used for work purposes. More lenient gram per mile emission

standards were developed that account for heavier loads and a potentially more rigorous duty

cycle of work trucks. However, it is now very common for trucks and SUVs to be used

primarily for personal transportation (i.e., as passenger cars), and light trucks (including SUVs)

have increased from 20% of the California vehicle market in 1980 to almost 46% in 1997. This

trend has a substantial impact on California's air quality because, although these vehicles are

used as passenger cars, they are certified to the more lenient gram per mile emission standards

designed for work trucks.

Since most pick-up trucks and SUVs have a curb weight less than 5,500 lbs. and a

payload of approximately 1,000-2,000 lbs., it is anticipated that the majority of the heavier trucks

will fall in the new LDT2 category below 8,500 lbs. GVW. (Although the same low-emission

vehicle standards will apply, the preexisting LDT1 category is retained because of the different

fleet average NMOG requirements described below and because only LDT1s are subject to the

ZEV requirements.) It appears unlikely that manufacturers will unnecessarily add payload to

trigger a numerically higher standard because of the negative impact on fuel economy,

performance and cost. In recognition of the fact that some of the heavier trucks in the new truck

category will be engineered for more rigorous duty, the regulations allow a small percentage (up
6

to 4%) of a manufacturer's truck sales in the LDT2 category to be certified to a marginally higher

NOx emission standard.

2. New LEV II Standards

The LEV II amendments establish new LEV II standards for the current LEV, ULEV and

SULEV categories. The LEV II standards, which are shown in Table 4, are more stringent than

the corresponding LEV I standards in several respects.

• Most importantly, the LEV II NOx standard for passenger cars and light-duty trucks

certified to the LEV and ULEV standards has been reduced by 75% from the prior

0.2 g/mi level to 0.05 g/mi. The 120,000 mile LEV II particulate emission standard is

0.01 g/mi for diesel LEVs, ULEVs and SULEVs, compared to 0.08 g/mi for LEVs

and ULEVs under LEV I.

• The overall LEV II emission standards for medium-duty vehicles have been tightened

to be substantially equivalent in stringency to the light-truck standards (although

numerically higher).

• The useful life for LEV II passenger cars and light-duty trucks has been increased

from the current 100,000 miles to 120,000 miles. Manufacturers must show

compliance with the full useful life standards over this mileage.

• A new light-duty SULEV category has been created with an NMOG standard less

than one-fourth of the level for ULEVs; recent technology developments indicate that

gasoline, alternative fuel and hybrid electric vehicles could potentially reach these

emission levels.

• Manufacturers will have the option of certifying any LEV, ULEV or SULEV to a

150,000-mile certification standard, in which case the vehicle will generate greater

NMOG credits for the fleet average NMOG determination. A manufacturer electing

this option will have to provide an 8-year/100,000-mile warranty for high cost parts

rather than for the normal 7 years/70,000 miles. (The 150,000-mile standards are not

shown in Table 4).

• Manufacturers can receive credit for the early introduction of larger trucks and SUVs

meeting a 0.2 g/mi NOx emission level and certified to the LEV I LEV and ULEV

standards; this credit can be used in the 2004-2008 model years on like vehicles

certifying to the LEV and ULEV 0.05 g/mi NOx standards. A similar option is

available for MDVs.

The Board eliminated the TLEV standards after the 2003 model year, concluding that the

more stringent standards for the other vehicle emission categories could be met by gasoline and

alternative fuel vehicles, and it was inappropriate to allow substantially higher NOx and

particulate levels to assure availability of diesel vehicles. In the 1999 model year, only a small

number of new diesel passenger cars were being sold in California, and no new diesel light-duty
7

trucks were being marketed. There were also no California diesel models in the MDV2 and

MDV3 categories that would be subject to the passenger car standards under LEV II; diesel

pickup trucks being sold in the MDV 4 and MDV5 weight categories would not become subject

to the passenger car standards and are not affected by elimination of the TLEV category.

Table 4: LEV II Exhaust Mass Emission Standards for New 2004 and

Subsequent Model LEVs, ULEVs, and SULEVs in the Passenger Car,

 Light-Duty Truck and Medium-Duty Vehicle Classes

Vehicle Type Mileage for

Compliance

Vehicle

Emission

Category

NMOG

(g/mi)

Carbon

Monoxide

(g/mi)

Oxides of

Nitrogen

(g/mi)

Formaldehyde

(mg/mi)

Diesel

Particulate1

(g/mi)

50,000 LEV 0.075 3.4 0.05 15 n/a

ULEV 0.040 1.7 0.05 8 n/a

LEV 0.090 4.2 0.07 18 0.01

ULEV 0.055 2.1 0.07 11 0.01

All PCs;

LDTs <8,500 lbs. GVW

120,000

SULEV 0.010 1.0 0.02 4 0.01

LEV 0.195 6.4 0.2 32 0.12

ULEV 0.143 6.4 0.2 16 0.06

MDVs

8501 – 10,000 lbs. GVW

(MDV4)

Vehicles in this category are

tested at their adjusted

loaded vehicle weight

120,000

SULEV 0.100 3.2 0.1 8 0.06

LEV 0.230 7.3 0.4 40 0.12

ULEV 0.167 7.3 0.4 21 0.06

MDVs

10,001-14,000 lbs. GVW

(MDV5)

Vehicles in this category are

tested at their adjusted

loaded vehicle weight

120,000

SULEV 0.117 3.7 0.2 10 0.06

Phasing in the LEV II standards. Over the 2004-2007 model years, manufacturers are

required to phase in certification of models to the LEV II emission standards in place of the

LEV I standards. For passenger cars and vehicles currently classified light-duty trucks, a

manufacturer must certify its vehicles to the LEV II standards at a rate of at least 25/50/75/100%

during 2004-2007. A manufacturer may use an alternative phase-in schedule if it achieves

equivalent NOx reductions by the 2007 model year. A manufacturer of vehicles classified as

MDVs under both LEV I and LEV II (8501 – 14,000 lbs. GVWR) must phase-in at least one test

group a year to the LEV II standards, with full compliance by the 2007 model year. Vehicles

that were treated as MDVs under LEV I but will be in the LDT2 category under LEV II – i.e. the

MDV2 and MDV3 categories – do not have to be certified to the LEV II standards until the 2007

model year, when 100 percent compliance is required. In California, the MDV2 and MDV3

categories each make up about 8% of the total number of vehicles that will be subject to the

passenger car standards under LEV II.
8

3. Requirements for phasing-in a cleaner vehicle fleet

For passenger cars and light-duty trucks, the LEV I annual fleet average NMOG

requirements continue to apply through the 2003 model year. The LEV II regulations provide

for continuing yearly reductions from the 2004 through 2010 model years as shown in Table 5.

Although each manufacturer can select its own vehicle mix, one approach in meeting the 2010

requirement for passenger cars and LDT1s would be a fleet made up of 18% LEVs, 47%

ULEVs, 25% SULEVs and 10% ZEVs. The fleet average NMOG levels are numerically higher

because no ZEVs are projected in this class and a longer phase-in period for ULEVs and

SULEVs is provided.

Table 5: LEV II Fleet Average NMOG Requirements for PCs and LDTs (g/mi)

Vehicle Category 2004 2005 2006 2007 2008 2009 2010+

PCs; LDT1s 0.053 0.049 0.046 0.043 0.040 0.038 0.035

LDT2s 0.085 0.076 0.062 0.055 0.050 0.047 0.043

For medium-duty vehicles, the requirement of a 60/40 mix of LEVs and ULEVs in 2004

and subsequent model years – shown in Table 3 – is changed to 40/60.

II. The Federal Tier 2 program

A. Background

The federal Tier 2 program grew out of requirements and limitations imposed by the

1990 amendments to the federal Clean Air Act (CAA). In 1990, Congress mandated the exhaust

emission standards that would apply to passenger cars, light-duty trucks and lighter medium-duty

vehicles after the 1993 model year. Passenger cars and light-duty trucks would be subject to

“Tier 1” standards essentially identical to the California standards applicable to 1994 model-year

vehicles – California’s use of the term “Tier 1” is actually borrowed from the federal program.

The Tier 1 standards were to be phased in over the 1994-1996 model-years. (CAA ' 202(g).)

The category of vehicles California calls MDV2 and MDV3 is called “heavy light-duty truck” or

“HLDT” under the federal program; these vehicles were to be subject to Tier 1 standards that

were phased-in over during the 1996 and 1997 model years. Again, these standards were

essentially identical to the California Tier 1 standards for these vehicle classes. (CAA ' 202(h).)

Congress prohibited U.S. EPA from adopting more stringent standards for passenger cars,

light-duty trucks and medium-duty vehicles prior to the 2004 model year. (CAA ' 202(b)(1)(C).)

Instead, the Clean Air Act directed U.S. EPA to conduct what became known as the “Tier 2”

study to examine the need for and technological feasibility and cost-effectiveness of more

stringent standards beginning between the 2004 and 2006 model years.

In February 1993, the 13 northeastern states making up the Ozone Transport Region

(OTR) submitted a petition to the U.S. EPA requesting the federal agency to require all OTR

states to adopt the California LEV program under section 177 of the CAA. In response, U.S.
9

EPA worked with vehicle manufacturers, various states and other parties to develop a “National

LEV” program, under which the manufacturers would voluntarily agree to market cars and light

trucks with emissions averaging at the LEV I LEV level in all states outside California. The

advantage to the OTR states was that not only would the vehicles sold in those states have

emissions substantially lower than under Tier 1, but the vehicles migrating in from other states

would be cleaner as well. The advantage to the automakers was that the National LEV program

would not require cars or light trucks meeting the California ULEV or ZEV standards. In

addition, the eight major automakers who had been subject to the California requirement for 2%

ZEVs starting in 1998 entered into Memoranda of Agreement with the ARB, committing to

offset the emissions loss in the state from postponement of the ZEV requirements by

participating in the National LEV program (or the equivalent) and thus assuring that cleaner cars

would migrate to California. U.S. EPA designed the National LEV program with the objective

that the additional benefits to the northeastern states from the introduction of cleaner cars

nationwide would be at least as great as the additional benefits from the states’ adoption of the

California LEV program with its ZEV requirements and its fleet average NMOG requirement

dropping below the LEV level starting in model-year 2000.

After much activity on a variety of fronts, U.S. EPA issued a final National LEV rule in

1997 (62 F.R. 31192 (June 6, 1997)) and a supplemental final rule in 1998 (63 F.R. 926 (January

7, 1998).) Ultimately, 9 of the 13 OTR states and all 23 vehicle manufacturers agreed to

participate in the National LEV program, which U.S. EPA found to be in effect in March 1998

(63 F.R. 11347 (March 9, 1998).) Four OTR states – New York, Massachusetts, Vermont and

Maine – chose instead to adopt the California LEV program pursuant to CAA section 177.

The National LEV program required the introduction of cleaner cars and light trucks in

the 9 participating OTR states starting in the 1999 model year, and nationwide staring in the

2001 model year (except for California and the four states administering the California program).

Manufacturers can certify vehicles to the California Tier 1, TLEV, LEV, ULEV and ZEV

standards, as long the fleet average reaches the LEV NMOG standards of 0.075 g/mi for

passenger cars and LDTs and 0.100 g/mi for LDTs by the 2001 model year. The National LEV

standards would were to end after the 2003 model year, or apply until Tier 2 takes effect,

depending on what action U.S. EPA took on Tier 2.

The National LEV program did not apply to the federal heavy light-duty truck (HLDT,

made up of LDT3 and LDT4) category, which is equivalent to California’s MDV 2 and MDV3

categories. Through the 2003 model year, these vehicles were subject to Tier 1 exhaust emission

full life NOx standards of 0.98 g/mi (LDT3/MDV2) and 1.53 g/mi (LDT4/MDV3); the 50,000

mile NOx standards were 0.7 g/mi and 1.1 g/mi respectively.

B. The Federal Tier 2 Regulations

On December 21, 1999, the U.S. EPA issued its Tier 2 regulations, which establish new

more stringent exhaust emission requirements for all U.S. light- and medium-duty vehicles not

subject to the California standards. (65 F.R. 6698 (February 10, 2000).) Although differing in

several respects from the California program, the Tier 2 regulations were designed to be

compatible with LEV II and to allow harmonization of federal and California vehicle technology.
10

Like the LEV II regulations, the Tier 2 regulations are complex, reflecting U.S. EPA’s interest in

providing vehicle manufacturers with as much flexibility as possible given the overall emissionreduction goals. The key elements of the Tier 2 exhaust emissions requirements are:

(1) A set of 10 different emission standard “bins” for cars and light trucks that function in

the same manner as the vehicle emission categories (e.g. LEV and ULEV) in the

California program;

(2) A fleet average requirement for NOx instead of NMOG, under which all of the

vehicles subject to the car and light truck LEV II standards, along with heavier

“medium-duty passenger vehicles” (MDPVs), will have to meet a 120,000 mile fleet

average NOx requirement of 0.07 g/mi for each manufacturer when phase-ins are

complete starting in the 2009 model year; and

(3) Several interim phase-in requirements for various classes of vehicles, which in some

cases include interim standards and fleet average requirements.

1. The Tier 2 emission bins.

Tables 6 and 7 show the 10 Tier 2 emission standards bins, plus the eleventh bin that

applies only to pre-2008 MDPVs only. Except in the case of MDPVs, bins 9 and 10 apply only

through the 2006 model year. Bins 1 through 10 are available to vehicles in all weight

categories. Bins 8, 9 and 10 have optional less stringent NMOG standards that apply for

qualifying LDT4s and MDPVs only; for bin 10 that is the case with CO and HCHO as well. It is

expected that moderately well-controlled diesel engines in SUVs and pickup trucks could meet

the standards for the least stringent bins.

2. The final fleet average NOx requirements.

The Tier 2 regulations employ a fleet average requirement for NOx instead of NMOG.

When phase-ins are complete starting in the 2009 model year, all of the vehicles subject to the

LEV II standards for cars and light trucks, along with MDPVs, will have to meet a fleet average

NOx requirement of 0.07 g/mi for each manufacturer. The Tier 2 program includes a credit

feature similar to that in the LEV II program. In years when a manufacturer’s corporate average

NOx emissions fall below 0.07 g/mi, it will generate credits. It can trade or sell those credits to

other manufacturers or use them in years when its fleet average NOx level is greater than 0.07

g/mi.

3. Interim fleet average requirements for various weight categories.

All 2004 and subsequent model vehicles subject to the Tier 2 program must be certified

to the standards for one of the available emission bins. This means that no 2004 or subsequent

model HLDT may be certified to a 120,000 mile NOx standard greater than 0.6 g/mi. In

comparison, the California LEV I NOx standard for MDV3s is 0.9 g/mi NOx., and

manufacturers are allowed to certify California MDV3s to the 0.9 g/mi NOx standard through
11

the 2006 model year. In addition, various weight categories are subject to interim fleet average

phase-in requirements.

Table 6: Tier 2 Intermediate Useful Life (50,000 mile) Exhaust Emission Standards

(grams per mile)

Bin Number NOx NMOG CO HCHO PM

11 0.6 0.195 5.0 0.022 --

10 0.4 0.160 4.4 0.018 --

9 0.2 0.140 3.4 0.015 --

8 0.14 0.125 3.4 0.015 --

7 0.11 0.075 3.4 0.015 --

6 0.08 0.075 3.4 0.015 --

5 0.05 0.075 3.4 0.015 --

Table 7: Tier 2 Full Useful Life (120,000 mile) Exhaust Emission Standards

(grams per mile)

Bin Number NOx NMOG CO HCHO PM

11 0.9 0.280 7.3 0.032 0.12

10 0.6 0.230 6.4 0.027 0.08

9 0.3 0.180 4.2 0.018 0.06

8 0.20 0.156 4.2 0.018 0.02

7 0.15 0.090 4.2 0.018 0.02

6 0.10 0.090 4.2 0.018 0.01

5 0.07 0.090 4.2 0.018 0.01

4 0.04 0.070 2.1 0.011 0.01

3 0.03 0.055 2.1 0.011 0.01

2 0.02 0.010 2.1 0.004 0.01

1 0.00 0.000 0.0 0.000 0.00
12

1. Light-duty vehicles and light light-duty trucks (California passenger cars, LDT1s and

LDT2s)

During the 2004-2007 model years, the following percentages of a manufacturer's fleet of

passenger cars and LLDTs must meet the Tier 2 fleet average NOx requirement of 0.07 g/mi:

25/50/75/100%. During model years 2004-2006, the manufacturer’s remaining vehicles in this

class must meet an “interim non-Tier 2” fleet average NOx requirement of 0.30 g/mi. Modelyear 2001-2003 vehicles in this class are subject to the National LEV standards that are

equivalent to average full life NOx levels of about 0.3 g/mi for passenger cars and LDT1s and

0.5 g/mi for LDT2s. The manufacturer may also use an alternative phase-in schedule, and pre2004 model-year vehicles that the manufacturer elects to have subject to the Tier 2 standards will

generate NOx credits.

2. HLDTs (California MDV2s and MDV3s)

For HLDTs, the following percentages of a manufacturer’s fleet must meet an “interim

non-Tier 2” fleet average NOx standard of 0.20 g/mi over the 2004-2007 model years,

aggregated with any MDPVs: 25/50/75/100%. Model-year 2004-2006 HLDTs not certified to

the interim non-Tier 2 standard will have to be certified to bin 10 or another bin of greater

stringency; this has the effect of imposing a NOx cap of 0.60 g/mi. starting with model-year

2004. During model-year 2008, 50% of the manufacturer’s HLDTs will have to meet the Tier 2

fleet average NOx requirement of 0.07 g/mi, with the rest meeting the interim non-Tier 2 fleet

average NOx requirement. All 2009 and subsequent model-year HLDTs will be counted under

the fleet average NOx requirement of 0.07 g/mi. This category of vehicles is not included in

National LEV, so 2001-2003 model-year HLDTs were subject to Tier 1 standards that permit

NOx emissions of 0.98 g/mi for LDT3/MDV3s, and 1.53 g/mi for LDT4/MDV3.

3. MDPVs (portion of California MDV4s)

MDPVs are basically grouped with HLDTs during the model years 2004-2009 phase-in.

During model years 2004-2007, a manufacturer of MDPVs must certify them to the fleet average

NOx requirement of 0.20 g/mi, aggregated with the manufacturer’s HLDTs, based on a phase-in

of 25/50/75/100%. During these years, the remaining MDPVs may be certified to bin 11 with its

120,000 mile NOx standard of 0.9 g/mi.