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U.S. Department of Transportation U.S. Department of Transportation Icon United States Department of Transportation United States Department of Transportation

Federal Exhaust Emission Certification Standards for Newly Manufactured Gasoline- and Diesel-Powered Light-Duty Vehicles

(Grams per mile)

Embedded Dataset Excel:

Dataset Excel:



KEY: CO = carbon monoxide; CVS = constant volume sampler; HC = hydrocarbons; NMHC = non-methane hydrocarbons; NMOG = nonmethane organic gases; NOx = nitrogen oxides.

a The test procedure for measuring exhaust emissions has changed several times over the course of vehicle emissions regulations.  The 7-mode procedure was used through model year 1971 and was replaced by the CVS-72 procedure beginning in model year 1972.  The CVS-75 procedure became the test procedure as of model year 1975.  While it may appear that the total HC and CO standards were relaxed in 1972-74, these standards were actually more stringent due to the more stringent nature of the CVS-72 test procedure.  Additional standards for CO and composite standards for NMHC and NOx tested under the new Supplemental Federal Test Procedure will be phased-in beginning with model year 2000; these standards are not shown in this table.

b All emissions standards must be met for a useful life of 5 years/50,000 miles.  Beginning with model year 1994, a second set of emissions standards must also be met for a full useful life of 10 years/100,000 miles; these standards are shown in parentheses. Tier 1 exhaust standards were phased-in during 1994-96 at a rate of 40%, 80%, and 100%, respectively.

c The cold CO emissions standard is measured at 20 0F (rather than 75 0F) and is applicable for a 5-year/50,000-mile useful life.

d The "Prior to control" column reports emissions estimates of a typical newly manufactured car in the years before exhaust emissions certification standards were implemented.

e No estimate available.

f Manufacturers can opt to certify vehicles for a full useful life of 15 years/150,000 miles and have either 1) intermediate useful life standards waived or 2) receive additional NOx credits.

g In 1968-69, exhaust emissions standards were issued in parts per million rather than grams per mile and are, therefore, incompatible with this table.

h No standard has been set.

I The term "tier" refers to a level of standards and is associated with specific years.  Interim Tier 2 refers to an intermediate level of standards that move manufacturers toward compliance with Tier 2 standards.   Interim Tier 2 and Tier 2 standards are established as "bins."  Each bin is a set of standards for NOx, CO, NMOG, formaldehyde, and particulate matter; HC and NMHC standards are dropped for Tier 2 and Interim Tier 2.  Manufacturers may certify any given vehicle family to any of the bins available for that vehicle class as long as the resulting sales-weight corporate average NOx standard is met for the full useful life of the vehicle.  The Tier 2 corporate average NOx standard is 0.07 grams/mile.  Interim corporate-based average NOx standards are based on vehicle type.  The interim sales-weighted average for light-duty vehicles (LDVs) is 9.3 grams/mile.  For LDVs, Tier 2 standards will be phased in at a rate of 25% in 2004, 50% in 2005, 75% in 2006, and 100% in 2007.  During this period, all LDVs not meeting the Tier 2 standards must meet Interim Tier 2 standards.


40 CFR 86, Subpart A (July 1, 2000).

Federal Register, Vol. 65, No. 28, pp. 6851-6858.