The Environmental Protection Agency is about to propose tighter vehicle emission standards yet again. Observers say the EPA rules would drive up the prices of the light trucks and sport utility vehicles to which they would apply.

While the new regulations have not been finalized, the EPA seems likely to:

• Require light trucks to meet largely the same emission requirements as cars.

• Require refiners to produce gasoline which has lower levels of sulfur -- which clogs catalytic converters.

• Allow continued use of some diesel engines -- which are expected to lead to more fuel-efficient cars.

• Apply the new rules to 2004 model-year vehicles and set tailpipe emission standards for a decade or more.

Experts say the resulting higher costs would be a major blow to auto makers -- particularly General Motors, Ford and DaimlerChrysler, which now garner much of their profits from popular truck and sport utility vehicles.

The proposed regulation is likely to employ a California-style "fleet average" emissions standard, perhaps phased in over a few years.

Source: Anna Wilde Mathews, "Popular Vehicles May Face EPA Hitch," Wall Street Journal, February 5, 1999.