Office of Transportation EPA420-F-06-027
and Air Quality March 2006
United States
Environmental Protectior
Agency
Regulatory
Announcement
Light-Duty Diesel Tier 2 Amendments
The U. S. Environmental Protection Agency (EPA) is making minor
amendments applicable to light-duty diesel vehicles under the Tier
2 program. The alternative compliance options will last for only
three model years (MY) — 2007 through 2009 — during which time
advancements in diesel emissions control technologies will be further
developed. The two voluntary compliance options would affect a very
limited set of standards for nitrogen oxides (NOx), including only high
altitude and high speed/high acceleration conditions. These temporary
options are designed to be environmentally beneficial. Any vehicle
certified to these options, while allowed to meet a less stringent NOx
standard when new, would have to meet a 30 percent more stringent
NOx standard and a 50 percent more stringent particulate matter (PM)
standard for their entire regulatory life. Further, that regulatory life would
be extended from 120,000 miles to 150,000 miles.
Background
In 2000, EPA's Tier 2/Gasoline Sulfur final rule established a program
to significantly reduce the emissions from new passenger cars and light
trucks, including pickup trucks, vans, minivans, and sport-utility
vehicles. The program reduces emissions by phasing in a single set of
exhaust emission standards that applies to all light-duty vehicles (LDVs),
light-duty trucks (LDTs) and larger passenger vehicles. To enable Tier 2
vehicle emission control technologies to be introduced and to maintain
the program's effectiveness, EPA also requires reduced gasoline sulfur
levels nationwide.
-------
Under the Tier 2 program, manufacturers
have the flexibility to certify Tier 2 ve-
hicles to different sets of exhaust emission
standards that EPA refers to as "bins." The
Tier 2 program implements a structure that
has eight emission standard "bins." Each
bin represents a set of standards to which
manufacturers can certify their vehicles.
Manufacturers have to choose the bins so
that their corporate sales-weighted average
NOx level is no more than 0.07 grams per
mile (g/mi).
The program treats vehicles and fuels as a
system, combining requirements for much
lower emitting vehicles with requirements
for much lower levels of sulfur in gasoline.
While the Tier 2 program did not require
similar changes for sulfur levels in diesel
fuel, EPA has mandated the reduction of
highway diesel fuel sulfur levels beginning
in June 2006. A key component of the Tier
2 program is an emphasis on consistent
emission standards regardless of fuel type.
However, the Tier 2 program also gives
some consideration to the fact that diesel
vehicles must accomplish a much greater
emission reduction from Tier 1 levels in
which emissions from diesel-powered ve-
hicles could be more than twice as high as
gasoline vehicles for NOx and, in practice,
were almost ten times higher for PM.
As EPA projected, the automotive industry
has made rapid advancements in diesel
emissions control technologies for NOx
and PM, enabling manufacturers to pro-
duce diesel vehicles that comply with the
primary regulatory requirements of the
Tier 2 program. Because diesel vehicles
still face some very limited technologi-
cal challenges in meeting the full suite of
Tier 2 requirements, EPA is providing very
limited flexibility.
These two narrow areas of emissions
control are the most challenging for diesel
vehicles due to the relatively high engine
loads of the high speed/high acceleration
test cycle (known as the US06 test cycle)
and the relative lack of oxygen at high alti-
tudes. The new technologies that have been
applied to bring these vehicles into Tier 2
compliance will require further fine-tuning
to fully address emissions under these con-
ditions. EPA is projecting that, with only
a few more interim years of refinement,
manufacturers will meet the remaining nar-
row challenges facing diesel technology.
Of
This direct final rule (and concurrent
proposal) contains two voluntary alterna-
tive compliance options for 2007 thru 2009
model year diesel vehicles: the "US06 Op-
tion" and the "High Altitude Option."
Option
« An LDV would be allowed to meet a
slightly higher 4,000 mile US06 stan-
dard for NOx + non-methane hydrocar-
bons (NMHC) (i.e., 0.25 g/mi vs. 0.14
g/mi).
* In return, any such vehicle must:
o Meet a Supplemental Federal Test
Procedure (SFTP) composite NOx
+ NMHC standard that is about
30% cleaner than otherwise re-
quired (e.g., for a bin 8 vehicle,
0.51 g/mi versus 0.71 g/mi).
o Extend the regulatory useful life of
this standard from 120,000 miles to
150,000 miles.
-------
High Altitude Option
• A bin 7 or bin 8 vehicle, at high alti-
tude only, would be allowed to meet a
slightly higher in-use NOx standard of
1.2x the Federal Test Procedure (FTP)
standard to which it is certified. The
vehicle's certification standards would
remain unchanged.
• In return, any such vehicle must:
o Meet a PM standard that is 50%
cleaner than otherwise required.
Such vehicles must meet the bin 5
PM standard of 0.01 g/mi vs. the
bin 7/8 PM standard of 0.02 g/mi.
o Extend the regulatory useful life
of all FTP standards from 120,000
miles to 150,000 miles.
Health and Environmental
Effects
No adverse health or environmental ef-
fects are expected from this rulemaking.
The compliance options are designed to
be environmentally beneficial. Diesel
vehicles making use of these options will
be cleaner than otherwise required. Auto
manufacturers would have the option to
certify diesel cars with slightly higher NOx
emissions during their first 4,000 miles of
operation (e.g., typically 3 to 4 months of
driving), but those cars must have overall
NOx emissions 30 percent cleaner over
their useful life compared to the permis-
sible levels without these optional provi-
sions. The optional provisions also require
diesel vehicles to reduce particulate matter
emissions by more than 50 percent. Both
options extend the regulatory life of the
vehicles to 150,000 miles. Diesel vehicles
certifying under these provisions will have
diesel particulate filters that reduce diesel
PM emissions to levels that previously
could only have been accomplished with
a gasoline engine. At the same time, these
diesel vehicles will maintain their historic
fuel economy advantage of 30 percent or
more relative to a gasoline vehicle.
For Information
You can access this rule and supporting
documents on EPA's Office of Transporta-
tion and Air Quality Web site at:
www. epa. gov/tier2/am endments.htm
For additional information, please contact
Robin Moran at:
U.S. Environmental Protection Agency
Office of Transportation and Air Quality
2000 Traverwood Drive
Ann Arbor, MI 48105
734-214-4781
E-mail: moran.robin@epa.gov
------- |