DETROIT -- Diesel engines from four automakers have passed the Environmental Protection Agency's stringent 2007 emissions regulations for cars.
Toyota Motor Corp. and Volkswagen AG are two of the automakers who have met the 2007 standards.
The development marks a shift in focus on diesels for the U.S. market from the technological challenges of meeting emissions regulations to reducing the cost of the powertrain.
The emissions systems on the four engines still need to pass durability tests to ensure no falloff in performance for 10 years or 150,000 miles before they can be certified for sale in the United States.
Fuel-efficient diesels are a leading technology to help automakers meet rising fuel-economy standards, especially for light trucks, which must average 22.2 mpg by 2007, up from 20.7 mpg today. The technology is particularly favored by European automakers, which already build diesels in high volume for Europe.
Low-sulfur fuel is key
At a Society of Automotive Engineers conference on diesels in Troy, Mich., last week, Jeffrey Holmstead, EPA assistant administrator for air and radiation, said prototype cars that meet the 2007 standards are being tested now at the EPA's Ann Arbor, Mich., emissions laboratory. The rules require diesels to run as cleanly as gasoline engines.
"History has shown that with enough lead time, your engineers can meet stringent standards," he said.
The diesel engines from the four automakers that met the 2007 standards were tested using low-sulfur diesel fuel from Europe, with sulfur content of 15 parts per million. A similar blend will be available in the United States starting in fall of 2006.
Cost has become the primary roadblock to diesels in the U.S. market, said automaker and supplier representatives at the SAE conference.
"It's pretty clear that there is a small niche interested in new technology," said Graham Hoare, Ford Motor Co.'s director of powertrain research and advanced engineering. "The problem we have to wrestle with is that we have to make the leap. We have to make (diesels) cost-effective."
Officials at the conference estimated the cost of a turbocharged diesel engine and all of the required emissions equipment to be between $1,500 and $2,000.