The federal Environmental Protection Agency says it wants a 97% reduction in the amount of sulfur in diesel fuel, effective in six years. The much cleaner fuel is needed so diesel engines can achieve lower exhaust limits scheduled for 2007. Engine builders say the very clean diesel fuel, with 15 parts per million of sulfur vs. the current 500 ppm (250 ppm in California), is the only way they can make their diesels meet upcoming emissions regs.

But oil refiners claim it will be far too costly to produce, adding 20 cents or more per gallon to the fuel's price. And truckstops say it will be impossible to phase in the new fuel without installing new tanks and pumps. Several congressmen have introduced a bill that would outlaw the EPA's rules.

Meanwhile, EPA's authority to set stringent and costly Clean Air standards is threatened by court fights. Courts have ruled that EPA must take costs, not just health, into account, but the agency has appealed to the U.S. Supreme Court. Stay tuned.