Gov. Paul LePage this week added Maine to a growing number of states that have passed or considered special fees on hybrid and electric vehicles.

LePage and officials in other states raised concerns that high-efficiency or electric vehicles are not paying their fair share of road maintenance costs, which are funded largely through state and federal taxes on gasoline.

The governor did not outline any specific proposal, but said it’s an issue he thinks the Legislature will have to take up, as hybrids and electric vehicle adoption continues to grow.

For popular hybrid- and electric-only car models, Maine registrations have grown more than 80 percent since 2012.

But those models still make up only slightly more than 1 percent of all vehicles registered in Maine, as of June, according to a Bangor Daily News analysis of registration data from the Bureau of Motor Vehicles.

The analysis undercounts the total number of hybrid and electric cars registered in Maine. Municipalities do not collect information about the fuel source for these reports. For that reason, the Bangor Daily News analysis was limited to make and model combinations offered only as electric or hybrid vehicles.

The Toyota Prius, pictured here in a Tokyo showroom, is the most popular hybrid-only model in Maine. State data does not allow breaking out hybrid versions of car models offered as both hybrid and gasoline-only engines. REUTERS | Yuriko Nakao

Toyota’s flagship hybrid, the Prius, by far leads registrations in the state.

Garry Hinkley, director of the BMV’s Vehicle Services Division, said his office is working on a more detailed look at electric and hybrid vehicles, using individual VINs to separate hybrid models of certain common cars, such as the Toyota Camry or Ford Focus.

The growing share of hybrid and electric vehicles on the road has prompted various states to take up the issue, in various ways.

In 2015, the National Conference of State Legislatures reported that four states — Idaho, Wyoming, Georgia and Michigan — adopted new fees for electric and hybrid vehicles.

A failed 2009 referendum in Maine asked voters to cut the excise tax in half and eliminate sales tax on either hybrid vehicles, alternative fuel vehicles or cars getting more than 40 miles per gallon.

Oregon has taken a different approach to the same problem, NCSL reported, starting a 5,000 vehicle opt-in program allowing drivers to pay based on the miles they drive rather than gallons of fuel purchased.

Such a move makes the policy change not just about hybrids and electric vehicles but about more closely tying payment to the amount of wear an individual driver places on roads.

The discussion comes as some states already have in place incentives for electric vehicle adoption, in the interest of reducing greenhouse gas emissions. Some states also have electric utility incentives, setting lower prices for electricity used to charge vehicles.

The impact of electric vehicles on the power grid is an entirely separate can of worms, balancing concerns of straining the electric grid with the possibility that a fleet of electric cars could themselves become resources using smart grid technology.

While electric vehicles appear to remain a quite small segment of the cars on Maine roads, the infrastructure for those cars looks quite different than just years ago, based on electric vehicle charging station additions alone.

Some of those added in 2016 included a group of chargers ReVision Energy announced it was installing Wednesday at Hannaford Supermarkets, with a fifth on the way. The special charging stations included Level III chargers capable of powering a Nissan Leaf enough to travel 115 miles.

(As of July, just more than 100 Nissan Leaf vehicles were registered in Maine.)

Tesla continues to add charging stations for its vehicles along I-95 and at certain inns and bed and breakfasts, too, according to the latest data maintained by the U.S. Department of Energy’s Alternative Fuels Data Center.

If the Legislature does heed LePage’s call to take up the issue, it will add fuel to already raging battles in energy policy over: solar policy, small-scale renewable projects, regional natural gas expansion, opening the renewable energy credit market to large-scale hydropower facilities, incentives for biomass generators and offshore wind, and the governor and Maine utilities’ interest in rolling back parts of the law that broke up electric monopolies.