AUGUSTA – Hybrid cars could become more common on Maine’s roads if the state Board of Environmental Protection approves a new clean vehicle quota considered Thursday afternoon.

The board held a public hearing on whether to adopt a zero-emissions vehicle program, designed in California and used in several other states, which requires that 10 percent of total annual automobile sales meet stringent emissions standards.

Outside, hybrid car owners and environmentalists rallied in support of the “clean” technology, which produces 46 percent less emissions than conventional vehicles, they said.

The Department of Environmental Protection is advocating for the ZEV program, which the department included as a strategy for reducing greenhouse gas emissions in the state’s climate change plan, drafted this summer.

Environmentalists applauded the program Thursday, calling it crucial to improving the state’s dreadful air quality. However, several automobile manufacturers and dealers argued that market forces, rather than a state mandate, should determine which cars and trucks are sold in Maine.

For more than a decade, Maine has followed most of California’s vehicle emissions standards, which are stricter than federal law. However, Maine opted out of the zero-emissions quotas in 2000 because, at that time, electric vehicles were the only way to meet the standards, said Ron Severance of the DEP’s Air Bureau.

Even today the vehicles aren’t affordable or practical here because of the cold weather and long distances Mainers drive, he said.

But California has changed its law, allowing gasoline-electric hybrids, gasoline-powered vehicles with cleaner burning engines, and experimental fuel-cell vehicles to fill the 10 percent quota.

“These vehicles are on the road [in Maine], we just need more of them,” Severance said.

Adam Lee, whose family owns 10 auto dealerships in Maine, including several that sell hybrid Toyotas and Hondas, testified that his customers face a six- to eight-month waiting list for the cars. Customers who would like to purchase a hybrid often select something else when they learn of his 32-person waiting list.

“If we could get three or four times as many, we could sell them all,” Lee said.

Environmentalists testified that Maine dealerships would be given priority for hybrids if the state adopts the ZEV program. The Northeast States for Coordinated Air Use Management estimates that 400,000 hybrids will be available for sale in 2009, with half of those destined for current zero-emissions vehicle states.

But automobile manufacturers and the Maine Automotive Dealers Association worried that local businesses could be stuck with vehicles on their lots that they might not be able to sell. In Maine, 61 percent of vehicles sold are either pickup trucks or SUVs, while most cars that meet either the hybrid or clean gasoline standard are compacts, said Robert Babik, who works for General Motors in Detroit.

“California would be choosing which vehicles could be sold in the state of Maine,” he said.

Auto industry representatives downplayed the possible environmental benefits of ZEV, saying that hybrids likely would sell anyway because of high gas prices.

But environmental and public health lobbyists urged the board to approve ZEV, testifying that the increase in clean car sales could make a noticeable difference in the cleanliness of Maine’s air – crucial in a state that has the highest adult asthma rate in the nation, said Norm Anderson of the Maine Chapter of the American Lung Association.

If the board adopts the new program, it would have to be approved by state legislators before it could go into effect. The DEP’s proposal incorporates “lead time” to allow auto dealers to adapt, and thus, wouldn’t kick in until the 2009 model year.

The board also held a public hearing Thursday on a rule to require clean technology for heavy-duty diesel engines. Again, opposed by industry and supported by environmentalists, the rule would lock pending federal restrictions into Maine law. Many states, including most of New England, are pursuing state rules out of concern that the federal restrictions, which were pushed through at the end of the Clinton administration and are set to take effect in 2007, could be delayed or weakened under President Bush, Severance said.

The board has tentatively scheduled votes on both issues in early December.

Written comments will be accepted through Oct. 22 and can be sent to the Department of Environmental Protection, 17 State House Station, Augusta 04333-0017.