General Motors Co. is offering to provide a free loaner car to any Chevrolet Volt owners who are concerned about the safety of their vehicle following a series of fires that occurred in crash-testing of the electric vehicle and its batteries.
"Our customers' peace of mind is the most important thing. This technology should inspire confidence and pride and not fear and doubt," said Mark Reuss, president of GM North America. "It underlines our commitment to the vehicle and its owners."
Reuss said the vehicles are safe to drive and won't spontaneously catch on fire, even in a crash.
Federal officials on Friday launched a formal safety-defect investigation into GM's plug-in hybrid vehicle after crash tests on several Volts and their batteries resulted in fires. In one case, a fire that started in one of the test vehicles consumed three others parked nearby.
The National Highway Traffic Safety Administration said it was "concerned" that damage to the Volt's batteries sustained in tests designed to replicate real-world crash scenarios resulted in the vehicles catching fire.
The problem occurs when electricity is left stored in the batteries for some time following a crash, said Mary Barra, GM's senior vice president of global product development.
The automaker's engineers are working with safety regulators to better understand the problem, she said, adding that GM is confident the fires would not occur in batteries that are fully drained following a crash.
"You need to depower the battery," she said.
When electrical energy is left in a battery after a severe crash, it could be similar fire hazard to leaving gasoline in a tank after a car crash, Barra said.
When GM learns of a crash involving a Volt from the vehicle's onboard communications system, the automaker sends technicians to hook up equipment to drain the electricity from the battery.
The NHTSA said it was too soon to say whether its probe would lead to a recall, but it vowed to "take immediate action" if it found any unreasonable safety risk. Measures would include notifying consumers and ensuring that GM communicates with Volt owners.
The investigation comes as GM has pushed for wider adoption of the plug-in hybrid, which according to the Environmental Protection Agency gets an equivalent of 93 mpg. GM has sold more than 6,000 Volts since the car was rolled out in December 2010. The Volt, which won the Green Car of the Year award at the Los Angeles Auto Show last year, is designed to run off its batteries for about 40 miles. When the batteries run low, a gasoline engine kicks in and functions as a generator, powering electric motors and extending the range of the sedan to more than 300 miles.
GM and the NHTSA are looking at test data to attempt to determine the precise cause of the fires.
The latest tests were part of an initial probe begun after the NHTSA found a Volt it had crash-tested in May caught fire three weeks later.
In a series of follow-up tests, the NHTSA subjected three additional Volt batteries to a crash simulation last week, intentionally damaging the cars' battery compartment and rupturing their coolant lines. One battery caught fire about a week after the test. A second vehicle's battery "began to smoke and emit sparks" just hours after the impact, the agency said.
-- Jerry Hirsch
Photo: Chevy Volt electric vehicles and Opel Amperas come off the line at the General Motors Detroit Hamtramck Assembly Plant in Hamtramck, Mich. Credit: Getty Images