WORCESTER — In hopes of furthering the state's emissions goals, Gov. Deval Patrick announced a new rebate program Thursday to encourage sales of plug-in hybrid and electric vehicles.

The rebates, worth up to $2,500, are funded through $2 million raised in an auction for the Regional Greenhouse Gas Initiative.

"Anything that makes a purchase less expensive helps," said John O'Dell, senior editor and green car guru at Edmunds.com, a car-shopping website that tracks trends in the industry. "Electric (vehicles) aren't selling as well as some hoped they would."

While the details of the rebates are not yet finalized, Krista Selmi, a spokeswoman for the state's Office of Energy and Environmental Affairs, said in an email that the program will be "up and running by early summer."

It will apply to new vehicles only and, unlike a $7,500 federal tax credit program for plug-in electric vehicles, this state rebate will be available directly after sales rather than as a tax credit, she said. Vehicles must be registered in Massachusetts.

In October, the Patrick administration set a goal with seven other states that 15 percent of new vehicle sales by 2025 will be zero-emissions. According to national data from Edmunds.com, electric and plug-in hybrid vehicles account for 0.6 percent of auto industry sales.

According to a 2013 report by the Consumer Federation of America, households with a vehicle in 2012 spent nearly $3,000 on gasoline, almost 50 percent more than expenditures on home energy.

Based on its research, the organization said it was optimistic that there will be great advances in vehicles meeting rising expectations for fuel efficiency in cars.

"Consumer demand for more fuel-efficient vehicles is high and the nation is well on its way to adopting a more fuel-efficient vehicle fleet under the federal 54.5 mile-per-gallon standard," researchers reported.

Roping in non-plug-in hybrids, the CFA said in its report, more than 5 percent of vehicles bought in 2012 were hybrid and electric, showing a 100 percent increase in sales in four years.

Mr. O'Dell from Edmunds.com said the biggest factors holding back sales of electric and plug-in hybrids are the high price, uncertainty with plug-in (charging) stations, and relatively low gas prices.

"At some point, it becomes too expensive to buy relatively (gas) thirsty cars that still make up the bulk of the American car market," he said.

Henry Lee, director of the environment and natural resources program at Harvard University's John F. Kennedy School of Government, said sales are being restricted by the existing electric-vehicle technology.

"In the long term, the only way electric cars will make significant (increases in sales) is to reduce the battery cost," he said. "There's nothing on the horizon that says they're going to come down substantially in the near term."

Also on Thursday, Gov. Patrick announced that nearly $600,000 will be distributed to 16 municipalities and a handful of public institutions as a second round of funding for the Massachusetts Electric Vehicle Incentive Program.

The announcements were made during a stop at the Worcester Regional Transit Authority hub on Foster Street, next to Union Station. Gov. Patrick said he was impressed by the WRTA's "wicked cool" fleet of six electric buses, which have been on the road since December.

Contact Alli Knothe at allison.knothe@telegram.com. Follow her on Twitter @KnotheA