Putting the Brakes on Clean Cars Researchers agree that conventional high-sulfur gasoline can poison a catalyst. The same researchers found that the sulfur content of gasoline sold in many parts of the country is high enough to impair function of the advanced catalytic converter used in the LEVs to reduce pollution. Although the petroleum and refining industries maintain that the damage done to an LEV's catalytic converter from sulfur can be easily reversed, automobile makers and state regulators disagree. The automakers plan to have LEVs for sale in all states by 2001.
Most gasoline sold in the United States has fairly high sulfur levels.
On the other hand, California, the nation's smoggiest state, now has a statewide sulfur standard of 30-40 ppm. California's standard allows refiners to produce gasoline in batches that meet a sulfur content average of 30 ppm, so that in some cases, sulfur levels in gasoline can be as high as the state's sulfur cap of 80 ppm. Most northeastern states, also suffering from high ozone levels, sell reformulated gasoline with sulfur levels of 150 ppm. Studies conducted by EPA and industry groups show that sulfur can affect the LEVs advanced catalytic converter, rendering useless its ability to control emissions. As early as 1992, the Society of Automotive Engineers published several laboratory studies, in which various fuel types were fed through an advanced technology catalyst.