Introduction
Low EmissionVehicle (LEV) Standards
These California emission standards, which applied through model year 2003, were expressed using the following
emission categories:
• Tier 1
• Transitional Low Emission Vehicles (TLEV)
• Low Emission Vehicles (LEV)
• Ultra Low Emission Vehicles (ULEV)
• Super Ultra Low Emission Vehicles (SULEV)
• Zero Emission Vehicles (ZEV)
Car manufacturers were required to produce a percentage of vehicles certified to increasingly more stringent
emission categories, according to schedules based on vehicle fleet emission averages for each manufacturer. After
2003, Tier 1 andTLEV standards were eliminated as available emission categories.
The same standards for gaseous pollutants applied to diesel- and gasoline-fueled vehicles. Particulate Matter (PM)
standards applied to diesel vehicles only. Emissions were measured over the FTP 75 test and are expressed in g/
mile. The additional Supplemental FederalTest Procedures (SFTP) were phased-in in California between 2001 and
2005.
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