Sorting out Standards
Exhaust emissions standards limit the amounts
of key pollutants coming from a vehicle's tailpipe and leaks in
its fuel system. All new vehicles for sale in the United States
are certified to meet either Federal emission standards, set by
the U.S. Environmental Protection Agency (EPA), or California standards,
set by the California Air Resources Board (CARB). Four northeast U.S.
states—New York,
Massachusetts, Vermont, and Maine—adhere to California's vehicle
regulations. (Connecticut, New Jersey, Oregon, Pennsylvania, Rhode
Island, and Washington state have adopted California standards as
well and will soon implement them.) Federal standards apply to all
the remaining states.
Today, most cars and light trucks are certified
to two standards, one California and one Federal. This allows automakers
to sell their vehicles nationwide and still comply with both sets
of emissions regulations. However, the legal requirements for vehicle
certification are complex, and in some instances, vehicles can
be certified to a single Federal standard nationwide, or to a single
California standard sold only in limited areas. In the latter case,
these vehicles are most often PZEVs sold either only in California,
or to California and the "clean car states" that have
adopted California's vehicle regulations.
The principal tailpipe standards applicable to today's vehicles
are:
Federal Standards:
- Tier 1: The former Federal (EPA) standard; as of 2005, no longer
in use.
- Tier 1-D: The former Federal diesel standard; permits higher
NOx emissions than the Tier 1 standard; as of 2005, no longer in
use.
- Tier 2 bin 11: New Federal standard, applies only to large
trucks.
- Tier 2 bin 10: Least-clean Tier 2 bin applicable to cars.
- Tier
2 bins 9 through 6: (Progressively cleaner standards)
- Tier 2 bin
5: "Average" of new Tier 2 standards. NOx
emissions levels of all vehicles sold by each automaker must average
to the bin 5 NOx level or cleaner when standards are fully phased
in later in the decade.
- Tier 2 bins 4 through 2: (Progressively
cleaner standards)
- Tier 2 bin 1: The cleanest Federal Tier 2 standard.
Equivalent to a zero-emission vehicle (ZEV).
California Phase II Low-Emission Vehicle Standards
A new set
of Low-Emission Vehicle standards; generally cleaner than Phase I
Low-Emission Vehicle standards:
- LEV II: Low-Emission Vehicle, the least stringent of the new,
Phase II LEV standards. NOx emissions are one-quarter the level
of a LEV I-certified vehicle.
- ULEV II: Ultra-Low-Emission Vehicle,
a mid-level Phase II LEV standard. Hydrocarbon and carbon monoxide
emissions levels are nearly 50% lower than those of a LEV II-certified
vehicle.
- SULEV II: Super-Ultra-Low-Emission Vehicle, a California
standard even tighter than ULEV II, including significantly lower
NOx emissions and more durable control systems.
- PZEV: Partial Zero-Emission
Vehicle, compliant with the SULEV standard; additionally has near-zero
evaporative emissions and a 15-year/150,000-mile warranty on its
emission control equipment.
- ZEV: Zero-Emission Vehicle, a California
standard prohibiting any tailpipe emissions.
California Phase I Low-Emission Vehicle Standards
The former
set of Low-Emission Vehicle standards; generally less clean than
Phase II Low-Emission Vehicle standards.
- LEV I: Low-Emission Vehicle, an intermediate California standard
about twice as stringent as the now-expired Federal Tier 1 standard.
- ULEV
I: Ultra-Low-Emission Vehicle, a stronger California standard emphasizing
low HC emissions.
- SULEV I: Super-Ultra-Low-Emission Vehicle, a stronger
California applicable only to larger passenger trucks (SUVs, pickups,
etc.); emits approximately half as much as a ULEV I-certified truck.
Automakers also rate their vehicles for fuel
economy (miles per gallon—MPG) according to standard EPA
tests of simulated city and highway driving. Fuel economy standards
apply to manufacturers, rather than to individual vehicles. A manufacturer
can sell models of varying fuel economy so long as their average
fuel economy meets the standard. Light trucks (pickups, minivans,
and sport utilities) have a lower standard than passenger cars
and station wagons. A new vehicle's sales sticker shows its city
and highway MPG ratings; check these sticker MPG values to help
you match a vehicle on the lot to a model listed here on GreenerCars.com.
Higher fuel economy means lower fuel consumption, savings on fuel
costs, and reduced global warming emissions. Even in new vehicles,
tailpipe standards don't fully reflect pollution in real-world driving
conditions or the pollution associated with the fuel consumed. Therefore,
among models meeting a given tailpipe emissions standard, higher
fuel economy means lower total emissions of other pollutants as well.
Depending on where you live and how you use
the vehicle, you may want to give greater or lesser importance
to some factors over others. For this reason, our ACEEE's Green
Book® Online database also
provides details on a vehicle's health impacts, its global warming
impacts, and its likely fuel costs. Buyers in urban areas, particularly
areas with air quality problems, should emphasize models that meet
tighter tailpipe standards, such as the California ULEV II or SULEV
II standards, or low-bin Federal Tier 2 standards (i.e., Tier 2 bins
2 through 4) noted above.
Green Buyer Alert
The pollution coming from a vehicle
depends on the standard it meets, how well its emissions controls
work, how it is driven and maintained, its fuel consumption, and
its fuel quality. Vans, pickup trucks, and sport utilities are classified
by the government as light trucks, and consequently have less stringent
fuel economy standards than passenger cars. As a result, the average
light truck pollutes more than the average car. Some of the heaviest
light trucks, such as large sport utilities, are not subject to fuel
economy standards at all, and are among the most polluting of personal
vehicles.
How to Tell which Emission Standard a Vehicle Meets
This year, models
can be certified to any of a host of emission standards, depending
on where they are sold and how clean they are. In 2004, a new set
of eleven Federal Tier 2 standards (called "bins")
went into effect, along with an updated set of California low-emission
vehicle (Phase II LEV) standards. As mentioned above, LEV standards
are required in California, Maine, Massachusetts, New York, and
Vermont. In other states, models are typically certified to one
of the Federal Tier 2 bins, although in some instances specific
models have been certified to a single Federal standard nationwide.
Regardless of where you live, however, identifying a vehicle's
emission standard is easy. Many automakers now list their cars'
and trucks' emission standards under the "Vehicle Specs" sections
of their Web sites. Some vehicles have stickers or window decals
identifying the certification level. All vehicles, however, have
a mandatory under-the-hood label that identifies the emission standard(s)—so
while you're standing on the dealer's lot, just pop the hood and
have a look.
GreenerCars.com lists (and scores) vehicles
under each emission standard to which they are certified. Often,
a single vehicle will be certified to both a Federal and California
certification so that it can be sold in different parts of the
country. We list such models as carrying dual certifications (e.g. "Tier 2 bin 5 / LEV II"),
and score them appropriately. If you're still unsure whether you
are matching your emission certification up properly, another double-check
is to compare the so-called Engine Family ID code. This is a 12-character
code (including decimal point) that will have a general format looking
something like "7FMXV02.0VZP". This also is required on
the under-the-hood label, and can be compared to the engine family
code that appears in the "Details" page for each model
listed in ACEEE's Green Book® Online.
Despite the details in this writeup, identifying
a vehicle's emission standard is actually a very simple process.
The only caveat is that the so-called "clean fuel fleet" certification
sometimes listed on the underhood label for regulatory purposes
should be ignored, as it will not be as accurate as the California
and Federal certifications.
Over the past few years, GreenerCars.com has identified vehicles
that were sold nationwide meeting one of the California certifications
by placing a star next to their emissions standard listing (e.g.,
LEV*). This proved helpful to consumers who lived outside California
but sought out the cleaner, low-emission vehicles. Today, because
most vehicles are now being sold carrying both a California and a
Federal certification, this nomenclature is largely outdated. Consequently,
we have discontinued this practice beginning with model year 2005
listings.
back to top
|
How to buy green
Sorting out Standards
Principal Tailpipe Standards
Federal Standards
California Phase II Standards
California Phase I Standards
Green Buyer alert
How to Tell which Emission Standard a Vehicle Meets
EPA Fuel Economy Estimation (Cars and Light Trucks)
Why Buy Green?
Automobiles and the environment
Glossary |
