DETROIT -- The battle lines are drawn: It's gasoline-electric hybrids vs. diesel engines in the race to improve fuel economy and lower emissions until the fuel cell displaces the internal combustion engine.
That's the conclusion of a panel of industry officials assembled at the SAE World Congress to discuss the future of the diesel engine.
Gasoline-electric hybrids such as the Honda Civic and Toyota Prius offer nearly 50 mpg in city driving. But they have expensive and complex powertrains, and the fuel economy gains on the highway are negligible.
Diesels, on the other hand, are more simple, offer great low-speed performance, and deliver higher fuel economy in city and highway driving. The problem: Diesels emit about 10 times more pollution than upcoming U.S. regulations allow.
But technology is being developed that should enable diesels to meet the toughest standards on the books, the so-called Tier 2 emission levels, which make no distinction between gasoline and diesel engines. Also, low-sulfur fuel, scheduled to arrive in 2006, will help lower diesel emissions.
|Title: Vice president, diesel fuel systems|
Company: Robert Bosch GmbH
Quote: "Diesel is the best interim solution until fuel cells arrive around 2020."
|Title: Director, diesel systems - North America|
Company: Siemens VDO Automotive
Quote: "Regulations will be there. We'll have to meet them."
|Title: Vice president, chief technical officer|
Company: Cummins Inc.
Quote: "It's extremely rare when a customer walks into a showroom and asks the salesman, 'How much does this baby emit?'"
|Title: Chief deputy executive officer|
Company: California Air Resources Board
Quote: "There is hope" for diesels.
The diesel cars on sale in the United States now - Volkswagen's Jetta, New Beetle and Golf - emit about 1.25 grams of NOx per mile, about 18 times more than the 2009 standards. Particulate matter, or soot, is another diesel pollutant that poses significant problems.
"There is hope," said Tom Cackette, chief deputy executive officer of the California Air Resources Board. Citing the Peugeot 607 sedan already on sale in Europe, Cackette said automakers can meet the most stringent regulations on the books. The Peugeot uses a NOx adsorber in the exhaust system to reduce emissions to 0.06 per mile and a particulate trap to collect soot before it leaves the tailpipe.
Peugeot "can meet Tier 2 standards. We consider them clean - at least for now. There's no reason to relax standards," Cackette said.
A test version of the Toyota Avensis sedan also meets the Tier 2 standards. But it is not clear if either vehicle could meet the EPA's long-term emission requirements, which call for no degradation of performance for 10 years or 150,000 miles - basically the life of the vehicle.
John Wall, vice president and chief technical officer at Cummins Inc., a diesel engine manufacturer, said his company has built and tested prototype V-6 and V-8 engines capable of meeting the tougher standards. But the challenge is to design emissions equipment robust enough to perform flawlessly and with no maintenance over the long term.
Panelist Brian Fitzgerald, of Siemens VDO Automotive, a manufacturer of diesel fuel injection equipment and electronic engine controllers, said diesel engines are going to need more powerful computers with the ability to diagnose and continually recalibrate themselves.
None of the panelists expected the government to relax diesel emission regulations, even if gasoline prices remain high. Diesel delivers about 30 percent better fuel economy than gasoline engines. And they could ease the country's dependence on imported oil.
"Regulations will be there," Fitzgerald said. "We'll have to meet them.
"Ultralow sulfur fuel is the enabler," he said.
With the cleaner fuel, sophisticated fuel injection equipment - which can make as many five injections on a single piston stroke - is expected to reduce in-cylinder emissions.
Kevin DeHart, vice president of diesel fuel systems for Robert Bosch GmbH, said consumers will choose diesels over hybrids once they see how well diesel engines perform and compare prices.
"A 1 mpg improvement costs $130 with a diesel engine," he said. "With a hybrid, that cost is between $300 and $700. Diesel is the best interim solution until fuel cells arrive around 2020."