After more than a decade behind the wheel of her trusty Volvo, Ginny Welles bought a brand-new Chevrolet. It’s a four-door compact called the Bolt. And she got a screaming deal.

“At the time we bought, there was a federal incentive and a Massachusetts state incentive that reduced the price of the car to us by approximately $11,500,” said Welles.

Those rebates brought down the price of the car by nearly a third. But federal tax rebates on many models are phasing out, and a $1,500 Massachusetts electric vehicle rebate ends this month.

Welles, who works for the Conservation Law Foundation, thinks that’s a mistake.

“I think that any incentive you can give people to be open to making a switch is worthwhile,” she said.

Five years after the state started offering rebates, electric vehicles remain a rarity. Numbers from the Auto Alliance indicate that of the more than 5 million vehicles registered in Massachusetts last year, just under 10,000 were electric — less than half of one percent.

“It takes time for these technologies to be wider known and to really see uptake,” said Jessika Trancik, an associate professor of energy studies at MIT. "It’s not like it’s going to happen overnight, but we are seeing the trend in that direction, and the rebates seem to have played an important role in that."

She said rebates aren’t needed permanently, just long enough to turn a nascent trend into a tipping point for electric vehicle sales.

“It’s difficult to predict what’s going to happen, but I would say it’s a big risk to take,” she said, “to get rid of that policy and really to let up on any policy that is proven to have a positive impact.”

Trancik’s research shows that when drivers switch from gas to electric vehicles they cut their vehicle emissions by about a third. That environmental impact is a major selling point, as is the promise of lower maintenance costs.

“There’s no oil, there’s no muffler, there’s no spark plugs. All the things you repair over the first eight years of having a car, it doesn’t have any of those,” said Sean Mulkerrins, who sells electric vehicles at Quirk Chevrolet in Braintree.

Electric cars, however, often have a higher price tag than comparable gas models. And so, Mulkerrins said, when the rebate ends, he expects sales to take a hit. But he believes it will be short-term. Car manufacturers are ramping up electric vehicle production, and he said that’s going to mean more options, more charging stations and ultimately lower prices, as was the case with the Chevy Bolt’s predecessor, a hybrid called the Volt.

“I was reading about the Chevy Volt when it first came out. It was one of the few cars that I’ve ever read about that the sticker price went down after a few years,” said Mulkerrins. “Just because the production cost went down, the price of the vehicle went down.”

Price, of course, is not the only factor. By far, the best-selling electric vehicles in Massachusetts are Teslas — which cost anywhere from about $50,000 to more than twice that amount.