PORTLAND – Two Maine environmental groups unveiled a report Tuesday that suggests 20 ways that state government can cut gasoline costs and reduce global warming pollution.

Released by the Natural Resources Council of Maine and Environment Maine, the report offers a range of recommendations, including several that could hit consumers in the wallet.

One goal of the proposed policies is to make individuals pay the full costs of driving – costs, the groups say, that are today subsidized or passed on to others in the form of pollution and congestion. Another is to take into account global warming pollution when thinking about transportation.

Among the ideas is to place stricter controls on new development and growth, provide incentives for more fuel-efficient vehicles, increase the cost of parking, require high-mileage tires and calculate auto insurance rates by the number of miles driven, which would act like a higher gas tax and discourage people from driving.

“The recent surge in gas prices underscores that we have an unsustainable transportation system,” said Jennifer Andersen of the Natural Resources Council of Maine. “We can’t afford the price at the pump, and we can’t afford the price on the planet.”

She called the region’s transportation system unsustainable.

Positioned strategically alongside a covered bus stop on Congress Street in Portland, speakers used the passing buses as a moving backdrop to make their case for more transportation alternatives.

“Now we’re siphoning off General Fund money to deal with highway maintenance,” said Matthew Davis, an advocate with Environment Maine. “If we had a sustainable system such that gas taxes paid for highways in full, people would be paying the true cost of driving.”

According to the report, “Shifting Gears: 20 Tools for Reducing Global Warming Pollution from New England’s Transportation System,” the transportation sector is the largest emitter of greenhouse gas pollution in the state. In 2001, it produced almost 72 million metric tons of carbon dioxide, more than all the homes, businesses and industrial facilities combined. Most of that pollution comes from gasoline burned in cars, trucks and SUVs.

Joining in the release of the report was Peter Cavanaugh, the operations director for the Greater Portland Transit District or METRO, and Carey Kish, manager of GoMaine Commuter Connections.

The speakers called on increased support for mass transit, including rail and bus lines, as well as the use of new technologies to reduce pollution and smart-growth policies that fight sprawl.

METRO has put into service 13 new compressed natural gas buses that will reduce emissions compared to diesel and the system has opened its first compressed natural gas fueling station, which is open to anyone, Cavanaugh said.

GoMaine, which coordinates car pools and van pools around the state, has seen a 23 percent increase in people registered with its ride-share program in the past six months, Kish said. And $400,000 has been committed to the program to double the size of the state’s van-pool program.

“Car pooling helps commuters fill in where there is no transit service,” Kish said. “It gives commuters an immediate 50 percent reduction in their commuting costs, just by riding with one person.”

The report envisions a world less dependent on individual automobiles, with communities more interconnected and with more opportunities for walking and bicycling.

“We are seeing the effects of global warming already,” Davis said. “We need to make sure we’re making the smart decisions about the way we grow and the way we move people and goods in this state so that we’re not contributing anymore than we already are to global warming and air pollution problems.”