LEV (Low Emission Vehicle)
This is the original and "dirtiest" emission standard that passenger cars sold between 1994 and 2003 had to meet. (There were separate, dirtier standards for light trucks, vans, and SUVs.) In a typical year of driving (10,000 miles), a LEV car spews 75 pounds of carbon monoxide and 4 pounds of nitrogen oxides into the air. For a light truck, it's 97 and 9 pounds, respectively. (By comparison, newer LEV II vehicles produce 25 percent and 88 percent less, respectively.) The LEV rating was replaced by LEV II in 2004.

ULEV (Ultra Low Emission Vehicle)
Another older emissions rating, ULEV cars generate 13 percent fewer emissions than LEV cars. (There's likewise a separate, dirtier ULEV standard for trucks, vans, and SUVs.) Your typical ULEV car is a basic big bomber Audi, BMW, Buick, Crown Victoria, or Ford Explorer from 2004. Tool around in one of these babies for a year, and you'll belch 38 pounds of carbon monoxide and 4.4 pounds of nitrogen oxides into the atmosphere. (Haul around in a 2004 Chevy CK30, and we're talking 121 pounds of carbon monoxide and 15 pounds of nitrogen oxides. By comparison, a new ULEV II vehicle is 20 percent and 88 percent cleaner, respectively.) The ULEV standard was replaced by ULEV II in 2004.

Low Emission Vehicle