The Environmental Protection Agency yesterday proposed new rules designed to cut the emissions of soot and other smog-causing pollutants by 90 percent in super-large sport-utility vehicles and heavy-duty commercial trucks.

In addition, the agency said it also plans to force the nation's petroleum industry to produce cleaner diesel fuels.

The actions target the heaviest passenger trucks, such as Ford Motor Co.'s jumbo Excursion sport-utility vehicle and General Motors Corp.'s traditionally large and weighty Chevrolet Suburban sport-utility models. It also takes aim at big, over-the-road haulers, such as those made by Mack Trucks Inc. and DaimlerChrysler AG's Freightliner Corp. subsidiary.

In an earlier action in May, the EPA for the first time proposed rules requiring light-duty trucks--vans, minivans, pickups, and sport-utility vehicles weighing less than 8,500 pounds--to meet the same tough tailpipe-emission standards set for cars. But passenger vehicles, such as some Excursions, that weigh more than 8,500 pounds fall into a different weight class (the lower end of the heavy-duty group), which puts them outside of the jurisdiction of the rule proposed in May.

The EPA's newest proposal tries to close that loophole by requiring vehicles such as the Excursion and the Suburban to meet car tailpipe standards, too.

"Anyone who has ever driven behind a large truck already knows about the levels of harmful air pollution that can come out of the exhaust pipes," said EPA Administrator Carol M. Browner.

"This new strategy . . . would close any possible loopholes for the new, super-large SUVs now being built by ensuring that they also meet strict emission standards. As a result, Americans can have both cleaner air and the consumer choices they want in motor vehicles."

EPA's new strategy involves two phases, the first affecting all heavy trucks and sport-utility models, those weighing over 8,500 pounds, beginning in 2004. Phase-one regulations would require gasoline trucks to be 78 percent cleaner and diesel trucks to be 40 percent cleaner than today's models.

The second phase of the proposal could take effect as early as 2007. It would require the reduction of smog-causing nitrogen oxides by 75 percent to 90 percent below today's levels. Phase-two rules also would cut emissions of soot, or particulate matter, by 80 percent to 90 percent below today's levels.

Most automakers yesterday declined immediate comment on the EPA's proposal, saying that they haven't had a chance to study the suggested rules. Ford officials said the new standards would be expensive and difficult to implement under the proposed timetable, but they issued a statement saying that they will work with the agency "to improve air quality and do what's best for our customers."

Ford is building 25,000 Excursions this year. The company says it has orders for 40,000 of the jumbo sport-utility vehicles, which sell for about $46,000.

"The Ford Excursion and all of our SUVs are already 40 percent cleaner than required," said Kelly Brown, director of environmental engineering at Ford.

CAPTION: Ford's Excursion is one of the vehicles that could fall under the new rules.