TORONTO - Climate-conscious motorists who pilot a Prius or scoot around in a Smart car could find themselves parking for free or passing in the car-pool lane under an aggressive new incentive program unveiled Wednesday in Canada's most polluted province.

By this time next year, provided Ontario's Liberal government is re-elected in October, Ontario residents who buy environmentally friendly, low-emission cars and trucks would get a green-hued licence plate that entitles them to such possible perks as free parking and access to high-capacity commuter lanes.

The so-called "eco-licence'' plate is one of three green transportation policies that the province is hoping will encourage commuters and businesses alike to factor the environment into their spending decisions.

"This is another way of us helping Ontarians go green,'' Environment Minister Laurel Broten told a news conference.

"Now we're saying we're going to also put some more factors on that table to help you make a decision that's good for your family and good for the environment.''

Broten said the government will consult with vehicle manufacturers and environmental groups to design a rating system that identifies the cleanest cars, light trucks and commercial vehicles.

Drivers of those vehicles would get the special licence plate, which would entitle them to added rewards. Those incentives haven't been determined yet and will be chosen during the consultation process, said Transportation Minister Donna Cansfield.

Environmental Defence policy director Aaron Freeman said he's hopeful the idea will take off across Canada, and suggested that green-plated drivers should also get a break on their annual vehicle registration fees.

The program would have a lot of visual appeal, Freeman said, giving people a way to proudly showcase their commitment to environmental causes and provide peer pressure to motivate others on the highway to go green.

"There is a greatly heightened sense of awareness surrounding environmental issues and it has become, I think, an admirable trait to drive fuel-efficent vehicles and to have visible signs you are environmentally friendly.''

The sight of motorists whizzing past traffic in car-pool lanes and snagging free parking spots in downtown areas could also be a big incentive to influence purchases, he said.

Plus, it would also encourage multi-vehicle families to use their low-emission cars more often and drive their gas-guzzling trucks only when absolutely necessary, Freeman added.

The licence plates are expected to be launched by spring 2008.

The transportation plan also includes a $15-million pilot project to help businesses convert to more environmentally friendly technologies, like hybrid power.

Some of that money will go toward cleaning up 1,000 medium-sized commercial vehicles, which have been identified as bad polluters, Broten said.

The province also plans to beef up its use of cleaner fuel for its own fleet of government vehicles by installing two new ethanol fuelling stations in London, Ont., southwest of Toronto, and Peterborough, an hour's drive northeast.

The new facilities could also be made available to municipal fleets once they're operational.

New Democrat critic Peter Tabuns said he was unimpressed by the announcement, which he called "small potatoes given the scope of the problem before us.''

"It's a pretty minor item -- I don't know if it'd call a press conference over something like this,'' he said of the new plate.

"My guess is it would be a very minor impact in terms of people's decision-making in these matters.''

But Broten said each little action can have a significant, cumulative impact in protecting the environment.

"All of those steps add up, all of those steps count -- they give all Ontarians the opportunity to make choices that contribute to a healthier environment.''

Conservative critic Laurie Scott said she has her doubts about the government's motives, given that they're announcing the plan in the dying weeks of their four-year mandate.

"They're asking for consultation and they've been here for four years,'' Scott said. "It's ridiculous what have they been doing. They're holding photo ops for consultations that could've happened anytime in the last four years.''