Automobile manufacturers have called on Congress and the U.S. Environmental Protection Agency (EPA) to avoid delays in implementing a proposed "clean diesel" rule for heavy-duty engines and diesel fuel. The Senate Environment and Public Works Subcommittee on Clean Air is holding a hearing on the rule September 21.

"Since EPA proposed the clean diesel rule last spring, efforts to delay and water down the provisions have intensified. If these delay tactics are successful, it will be a huge setback for cleaner air," said Alliance for Automobile Manufacturers President and CEO Josephine S. Cooper. "We encourage EPA to stand by its proposal and finalize a strong clean diesel rule by the end of the year."

Cooper noted that recent economic studies on making and distributing ultra-low sulfur diesel fuel have overstated the costs and difficulty of bringing this clean fuel to market. "We have great confidence in the oil industry's ability to meet the requirements of EPA's proposed rulemaking by 2006," Cooper continued. "Getting the sulfur out of diesel fuel will dramatically improve air quality, and it will enable us to develop a new generation of clean, light-duty diesel vehicles that are more fuel-efficient. These clean diesel vehicles are coming soon, and we need clean diesel fuel to run them."

"Clean diesel" refers to vehicles with diesel engines using clean diesel fuel together with emission control systems to reduce substantially emissions of particulate matter, nitrogen oxides and other pollutants.

EPA's heavy-duty vehicle rule, which includes reducing sulfur in diesel fuel, was proposed on May 17, 2000 and is expected to be finalized by the end of the year. Under EPA's proposal, refiners must reduce the sulfur in diesel fuel by 97 percent within six years, and this cleaner fuel must contain no more than 15 parts per million (ppm) of sulfur. EPA's proposal also calls on heavy duty engine manufacturers to achieve a 95 percent reduction in nitrogen oxide (NOx) emissions phased in during 2007-2010, along with a 90 percent reduction in particulate matter (PM).

"Alliance members have made the call for low sulfur fuels a crusade because clean fuels are needed to run clean vehicles for clean air," Cooper said. Because of the high sulfur content of diesel fuel, vehicles with heavy- duty engines, such as trucks and buses, have not been able to use state-of- the-art emission control technology. In addition, low sulfur diesel fuel would provide immediate clean air benefits when used by the millions of trucks and buses already on U.S. roads. In Europe, several countries are already moving toward ultra-low sulfur content in fuels through incentives. (For more information visit

The Alliance is supporting elements of EPA's proposed rule, but calls on the Agency to go farther. EPA has proposed to cap sulfur in diesel fuel at 15 ppm by mid-2006, but manufacturers want near-zero sulfur content -- 5 ppm, along with improvements in other fuel parameters as recommended in the fuel charter endorsed by all of the world's automakers. This ultra-clean fuel enables manufacturers to introduce advanced aftertreatment devices for both heavy and light duty diesel vehicles. Recent reports from the Department of Energy's Diesel Emission Control Sulfur Effects (DESCE) Program underscore the critical need for ultra-low sulfur, showing that even a few parts-per-million sulfur greatly impairs vehicle exhaust aftertreatment systems.

EPA has stated that under its proposed plan, " ... diesel vehicles would achieve gasoline-like exhaust emission levels, in addition to their inherent advantages over gasoline vehicles with respect to fuel economy, lower greenhouse gas emissions and lower evaporative hydrocarbon emissions." EPA's rulemaking is also supported by state and local air pollution administrators, environmental groups, public health organizations and engine manufacturers. Tosco Corporation, the largest independent oil company in the United States, has also publicly expressed support for the rulemaking.

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