DETROIT — In a rare move, General Motors said Thursday that it would buy back Chevrolet Volts if owners were concerned about fire risks. It also promised to comply with any changes to its battery pack recommended by federal regulators.

In an interview with The Associated Press, G.M.’s chief executive, Daniel F. Akerson, defended the safety of the plug-in hybrid vehicle but said the automaker would purchase Volts from unsatisfied customers, reported The New York Times.

A G.M. spokesman, Rob Peterson, confirmed the buyback offer. “If there’s a customer that wants to sell back their Volt, we’ll buy it back from them,” Mr. Peterson said.

Such a buyback is unusual for car companies, which typically institute recalls when regulators or customers report problems with cars or parts. Ford, however, offered to buy back older model Windstar vans last year after investigations into rear axle problems.

The Volt has come under scrutiny after the National Highway Transportation Safety Administration said on Nov. 25 that it had opened a defect investigation into the car’s 400-pound battery pack.

The company on Monday offered free loaner cars to all Volt owners while a federal investigation continued into the potential for postcrash fires in the car’s lithium-ion battery.

Two Volt batteries caught on fire after crash simulations, the agency said. One fire occurred three weeks after the battery was damaged, and a more recent test resulted in a fire one week later. Another pack emitted smoke and a spark in the aftermath of a crash test.

In a separate interview with Reuters, Mr. Akerson said that G.M. would make changes to the Volt’s battery pack if they were recommended by federal officials.

Mr. Peterson said the company would alter the packs “if there’s an engineering solution required.”

Some Volt owners are not concerned about the inquiry. “It just has to be treated carefully in the event of a crash. I really am not worried,” Eric Rotbard, a Volt owner who is a lawyer in White Plains, said in an interview on Monday. “We just have to get more comfortable with the technology. It doesn’t seem to be any less safe to me.”

The latest developments came the same day that G.M. reported that November was the best month for Volt sales since the car was introduced late last year.

G.M. said it sold 1,139 Volts in November, bringing the year’s total to 6,142.

However, the company acknowledged for the first time that it would not achieve its target of selling 10,000 Volts this year, even after allowing dealers to sell demonstration models last month to increase inventory.

The head of G.M.’s Chevrolet division, Alan Batey, said that missing the sales target did not diminish the car’s positive effect on the brand.

“This vehicle is more than just how many do we sell every month,” Mr. Batey said in a conference call with reporters. “It is a magnet around everything we’re trying to do to showcase the brand.”

The Volt was the industry’s top-scoring model in this year’s Consumer Reports customer-satisfaction survey, the publication said Thursday, with 93 percent of owners saying they would buy one again.

G.M. executives have repeatedly defended the safety of the Volt since the federal inquiry opened, noting that there have been no reports of fires in real-world crashes.

The company has asserted that the bigger issue is how the lithium-ion battery is handled by emergency personnel and maintenance technicians after an accident.

G.M.’s product development chief, Mary Barra, said Monday that the car’s battery should be depowered immediately after a collision to avoid any possibility of a fire.

“This is not a conventional automobile,” said Joseph Phillippi, an industry analyst with the firm Auto Trends. “We are talking about high-voltage batteries, and they need special treatment.”

So far, 33 Volt owners have requested a loaner vehicle since the offer was made, and 230 people have contacted their dealers with questions, Mr. Batey said.