California air regulators on Friday unanimously approved the world's most ambitious rules to reduce the car emissions that contribute to global warming, a move that could bring sweeping changes to how the rest of the nation fights vehicle pollution.

The regulations are expected to cut exhaust emissions in cars and light trucks by 25 percent and in larger trucks and SUVs by 18 percent.

Their approval by the California Air Resources Board (search) came after nearly two full days of debate and discussion, during which the auto industry vigorously stated its opposition.

Industry officials argued that the board did not have the authority to adopt such sweeping regulations, that they couldn't be met by current technology, and that they unfairly targeted California, which produces less than 1 percent of the world's greenhouse gases.

Heat-trapping greenhouse gases are believed by many scientists to contribute to global warming.

The proposals would require automakers to reduce emissions by using such technological innovations as better air conditioners, more efficient transmissions and smaller engines.

Among those supporting the regulations was Gov. Arnold Schwarzenegger's (search) environmental protection secretary, Terry Tamminen, who said Friday he and Schwarzenegger believe California should do its part to reduce pollution. He strongly urged the board to adopt the proposals.

"We can make it clear that yes, we understand that our contribution, no matter how large or small, makes a difference," Tamminen said. "Every single action that we take -- or inaction -- makes a difference."

Gloria J. Bergquist, a spokeswoman for the industry trade group Alliance of Automobile Manufacturers (search), said the regulations would only reduce worldwide emissions of greenhouse gases by "one-tenth of 1 percent."

"We see that as no apparent health benefit at a great cost to California consumers," she said.

Bergquist said manufacturers are already working to produce cleaner vehicles, but that introducing the technology required under the regulations would be "almost as complicated as developing the first automobile."

Asked after the vote if her group planned to sue to block the regulations, she said that was an option but no decision had been made yet.

The board's staff said the cost increases would top out at about $1,000 per vehicle by 2016. Staff members studied the automakers' estimates Thursday night, and said in a report issued Friday that the automakers' $3,000 figure was an exaggeration.

Air Resources Board Chairman Alan C. Lloyd and other board members said they were disappointed that automakers did not accept invitations to work with them on the regulations.

"The response, the silence, was deafening," Lloyd said. "We should be able to work together. I hope that we still can work together on this tremendously important issue. The stakes could not be higher."

Board member Mark DeSaulnier, a Contra Costa County supervisor, said he had slept fitfully the night before the vote because he felt "disappointment, frustration, and sometimes anger at the auto industry."

He objected to industry arguments that Washington, D.C., and not California, should lead efforts to fight greenhouse emissions -- and argued that automakers should have taken the lead themselves.

"If I had my druthers, it would be settled in Detroit," he said.

The proposals stem from a law signed by former Gov. Gray Davis in 2002 that required the board to set emission standards for greenhouse gases. The bill's author, Assemblywoman Fran Pavley, D-Agoura Hills, said Friday's vote marked the first time in the world regulations have been placed on vehicles for the specific purpose of reducing greenhouse gas emissions.

She said the fact the action had the support of Davis, a Democrat, and Schwarzenegger, the Republican who replaced him, "speaks to the unified effort among all Californians" to reduce greenhouse gases.

Board members said there is no dispute that greenhouse gases contribute to global warming that can harm California's economy in fields ranging from agriculture to tourism.

They said the emissions can also lead to serious respiratory problems, especially among children, by exacerbating the effects of smog. Los Angeles has the worst smog problem in the nation.

Board member Henry Gong, a physician, noted that many medical experts pushed for the regulations and none testified against them.