WASHINGTON -- U.S. automakers could nearly halve output of heat-trapping greenhouse gases by 2030 with new technology and more fuel-efficient models, a needed step to reverse growing emissions from the world's No. 1 transportation sector, an environmental think tank said on Thursday.
The U.S. transportation sector -- comprising all cars, trucks, airplanes and ships -- generates more greenhouse gases than any other nation's total economy except for that of China, according to the Pew Center on Global Climate Change.
Transportation vehicles produce one-third of all U.S. greenhouse gases, the Pew Center said in a report.
"The U.S. is the owner of the world's largest transportation system, and reducing emissions from this system is critical to an effective greenhouse gas reduction strategy," said Eileen Claussen, president of the non-partisan, environmental research organization.
More than two dozen major companies such as automaker Toyota Motor Corp., oil major BP Plc and utility company PG&E Corp. have been working with the Pew Center on a range of options and policies to address climate change.
The report called on the United States to impose limits to rein in emissions of carbon dioxide, which scientists have linked to global warming. The White House previously rejected a cap on carbon dioxide in favor of voluntary industry efforts.
New technology for cleaner diesel engines and hybrid vehicles could cut gasoline use by 50 to 100 percent by 2030 without reducing vehicle weight or performance, the report said.
In the short term, fuel economy for new cars and light trucks could be boosted by 25 percent to 33 percent in the next 10 to 15 years with existing technology, the report said.
Booming popularity of SUVs has dropped the average fuel economy of new U.S. vehicles from 25.9 miles per gallon in 1988 to 24 mpg in 2002, the center said. U.S. automakers have resisted stricter fuel standards, saying that would mean using lighter, flimsier materials that make vehicles less safe.
The Bush administration's initiative to build a hydrogen-powered car could bear fruit in the long term, but immediate action is needed, the Arlington, Va.-based group said.
Republican Sen. John McCain of Arizona and Democratic Sen. Joseph Lieberman of Connecticut want to amend a wide-sweeping energy bill before the Senate to establish a clear limit, but McCain has conceded that the plan has little hope of passage.