SAN FRANCISCO - The head of California's air quality board on Thursday called proposed rules that would require automakers to build less-polluting cars and trucks by 2025 a historic move for a cleaner environment.

California Air Resources Board Chairman Mary Nichols said she hopes the rules to require that vehicles emit about 75 percent less smog-producing pollutants will "lead the nation and the world."

The new standards, which also include big cuts in greenhouse gas pollutants, would begin with new cars sold in 2015, and get increasingly more stringent until 2025. The rules also mandate that one of every seven new cars sold in 2025 in the state be a zero-emission or plug-in hybrid vehicle.

"We can't afford to wait. We have to act on these issues now," she said at the panel's meeting. "Our projections show continued growth in population and vehicle miles traveled, which will affect air quality for years to come."

The state's smog emissions standards are often more strict than federal ones, which means other states often adopt them as their own.

Fourteen other states, including Washington, New Jersey, New York and Massachusetts, have adopted California's current emissions goals, which is why the new regulations could have a wide-ranging effect. Of those states, 10 also adopted the zero-emission vehicle standards as well.

The regulations, which could be voted on as early as Thursday, will continue the state's first-in-the-nation greenhouse gas emissions standards for cars and trucks, which went into effect in 2009. This time, the greenhouse gas reduction element was designed with federal regulators so that it will match national standards expected to be passed later this year.

"When we did the first greenhouse gas standards, it was war," said Tom Cackette, deputy director of the board, referring to legal challenges from auto dealers and business groups after the state passed the initial greenhouse gas emissions limits.

"They sued us in two federal courts. Fortunately, from our viewpoint, they lost. Over that time, with the increase in gas prices, the shake-up in the auto industry brought new management which looked at the future. Where's our future? It's not profits next quarter but how do we make a sustainable business."

In addition to new smog and greenhouse gas emissions limits, the regulations being voted on also includes a new zero-emissions vehicle mandate. The goal is to have 1.4 million zero-emission and plug-in hybrids on California roads by 2025. But the program also looks ahead to 2050, laying groundwork for a goal of having 87 percent of the state's fleet of new vehicles fueled by electricity, hydrogen fuel cells or other clean technologies.

"This regulation is planned over a 40-year horizon, and that is extremely unusual," said board spokesman David Clegern. "But it gives us time to put the pieces in place with no surprises. The individual companies can plan for changes and develop the technology, and over the long haul, it will shift us away from reliance on petroleum."

The board's meeting comes just three days after federal regulators met in San Francisco to hear public comment on the Obama administration's national fuel economy standards, the most far-reaching in history. If passed later this year, they would require the average passenger car to reach a 54.5-mph standard by 2025.

The U.S. Environmental Protection Agency, 13 automakers, CARB and others worked together so that when the federal government passes its greenhouse gas emissions limits later this year, they will match California's and create one national standard.

Some automakers said the market for clean car technology is already spurring the technology and innovation the regulations seek to influence.

"Yes, the cars will be lighter, compact, far more fuel efficient. That's what the mandate will be. It's not enforced by the government but really by the economics of the future," said Michael Dobrin, a spokesman for Toyota.

Yet some auto dealers have argued that the government's emphasis on strict pollution controls will result in much higher prices for consumers.

Forrest McConnell, director of the National Automobile Dealers Association, testified during the federal hearing Tuesday that tightening fuel efficiency standards will result in unaffordable cars.

"We all want better fuel economy, but it is not free. By adding $3,200, if not more, to the average cost of a car, over seven million Americans will be priced out of the market, fleet turnover will be reduced, and public policy benefits will be delayed," McConnell said.

Other dealers say consumer demand for electric and hybrid vehicles is not what the board hopes it is.

The California New Car Dealers Association says hybrid vehicles, which have been marketed and sold for 13 years, only make up 2.1 percent of the national market, and 4.1 percent of California's market. They say the goal of making one of every seven new cars sold in California a zero-emission vehicle in roughly the same amount of time is unrealistic.

"Rather than setting vehicle manufacturers, new car dealers, and alternative vehicles themselves up for another predictable failure, (the board) should adjust the mandate to reflect a goal that is realistic and attainable," said Jonathan Morrison, the state dealers' association's director of legal and regulatory affairs.

The air board's research and environmental advocates dispute those cost increase estimates, and say increases in hybrid and other sales continue to rise as more cars hit the market. They argue that fuel cost savings will make up for any vehicle price increase.

"Our research shows a $1,400 to $1,900 car price increase, but over the life of the vehicles, the owners save $6,000 in reduced fuel and maintenance costs," said Clegern.

One of the nation's foremost consumer groups, the Consumers' Union, which publishes Consumer Reports, voiced support for the regulations, saying in a letter that they will "protect consumers by encouraging the development of cleaner, more efficient cars that save families money, help reduce the American economy's vulnerability to oil price shocks and reduce harmful air pollution."