U.S. regulators, who ended their investigation yesterday into the Chevrolet Volt, said electric- powered vehicles do not pose a greater risk of fire than gasoline cars.

“Based on the available data, NHTSA does not believe that Chevy Volts or other electric vehicles pose a greater risk of fire than gasoline-powered vehicles,” the National Highway Traffic Safety Administration said in an e-mailed statement.

The conclusion by NHTSA came two weeks after General Motors Co. told Volt owners to bring the vehicles to dealerships for repair.

The government started investigating the Volt after a side- impact crash test in May led to a fire three weeks later. During that test, the lithium-ion battery pack broke open and coolant leaked into the battery. When the car was physically rotated as part of the test, more coolant leaked into a circuit board, leading to a fire. NHTSA replicated the fire in November and started an official probe Nov. 25.

“GM is proud of the technological innovation the Volt represents,” Greg Martin, a GM spokesman, said yesterday in an e-mailed statement. “We appreciate the confidence our Volt customers continued to provide during the investigation.”

The June fire occurred following a May 12 crash test at a facility in Wisconsin run by contractor MGA Research Inc., which notified the regulator that the blaze burned a line of cars parked near the Volt, NHTSA said yesterday in its report.

The agency and its investigators concluded in July that the fire originated in the Volt battery and performed another side- impact test on a Volt in September. That crash, which didn’t penetrate the battery compartment, didn’t lead to a fire. NHTSA, which tested Volt batteries in November with the Energy and Defense departments, hadn’t previously disclosed the September crash test.

The June Volt fire was reported Nov. 11 by Bloomberg.

The Volt blaze had little effect on sales of the vehicles, so there may not be any significant improvement with the government completing its investigation, said Jeremy Anwyl, vice chairman of auto-researcher Edmunds.com, in an e-mail.

“Volt buyers tend to be passionate about their vehicle,” Anwyl said. “They really want an electrified vehicle. The small risk represented by the potential for fire wouldn’t have been an obstacle for this group of buyers.”

The attention focused on the Volt fire was, in part, a result of the vehicle’s new technology, Anwyl said.

“We see gasoline powered vehicles blow up in the movies all the time,” he said. “A vehicle with batteries catches fire and it is portrayed as a big deal.”

Representative Darrell Issa, the California Republican who is chairman of the House Oversight and Government Reform Committee, plans to hold a hearing on Jan. 25 about the fires and the regulator’s handling of the incidents. GM Chief Executive Officer Dan Akerson and NHTSA Administrator David Strickland are scheduled to testify.

Issa has asked whether President Barack Obama’s administration kept silent about the fires because of its interest in the success of GM’s government-backed restructuring and a U.S. goal of having 1 million electric vehicles on the road by 2015.

U.S. Transportation Secretary Ray LaHood told reporters in December it was “absolutely not true” that his agency withheld information about the Volt’s safety.

GM, based in Detroit, said Jan. 5 it would provide a fix to the 8,000 plug-in hybrids it has sold, to reduce the risk of a post-crash fire. Strickland said in Detroit Jan. 8 that the agency was pleased with GM’s plan.

The Treasury Department owns 32 percent of GM’s stock, according to data compiled by Bloomberg.