GM offers loaners to Volt owners amid fire probe

— -- General Motors, responding Monday to a federal probe into fires after test crashes of its Chevrolet Volt, offered free loaner vehicles to owners concerned about the advanced-technology plug-in sedan.

GM officials said they're mailing letters to all 5,329 buyers of Chevrolet Volt to reassure them about its safety. The car will remain on sale, and its high-profile television ad campaign will continue.

The announcements follow the National Highway Traffic Safety Administration's announcement Friday that it has opened a formal investigation into the Volt. It said it was taking the action after three tests in which the car's lithium-ion battery heated up or caught fire days after simulated side-impact crashes.

The fires didn't break out immediately. They took days or weeks after the initial crash test, leading to warnings for tow operators and storage yards to make sure damaged Volts are parked away from buildings or other vehicles. No fires in customers' vehicles have been reported.

"We are contacting all Volt owners to assure them and reassure them the car is safe to drive," said Mark Reuss, head of General Motors North America, in a conference call with reporters. "The Volt is our pride and joy, and we will do all we can to make Volt owners as happy with it as we can."

The Volt is a plug-in car that runs on electricity for 25 miles or more. Then its gas engine kicks in to give it hundreds of miles range, just like a conventional car.

The $39,995 Volt was introduced last December, the same month that Nissan's all-electric Leaf sedan had its debut. Nissan says it hasn't had any similar fire issues or new federal inquiries involving Leaf's lithium-ion battery.

GM says the issue in the Volt appears to involve the car's electronics, not the battery.

Lithium-ion batteries — similar to those that power laptop computers and far mightier than the kind of batteries found in many hybrid cars — have to be kept cool. A serious accident that causes a coolant leak could lead the batteries to heat up and catch on fire, says John Frala, an automotive repair educator in Whittier, Calif., who serves on a Society of Automotive Engineers' panel developing procedures for police and firefighters who encounter crashes involving electric cars.

Overall, he says the batteries are safe. "We put nails through these things, and it still holds its voltage," he says.