Chevy Bolt EV's back seat fires prompt federal investigation

After two Chevrolet Bolt EV owners reported fires breaking out under the car's back seat, the National Highway Traffic Safety Administration is looking into the cause.

Two owners of 2018 and 2019 Bolt electric vehicles reported to the National Highway Traffic Safety Administration that the cars had caught fire under the back seat, in the battery compartment, while the car was parked. NHTSA researchers from the Office of Defects Investigation then found a third affected car: a 2017 Bolt with similar burn pattern in the backseat. So, last week, the federal agency opened an official investigation, a first for General Motors' only electric vehicle.

This means all Bolts from 2017 through 2020 will be scrutinized for a possible recall if a defective part or issue is discovered. In that time period there've been 77,842 Chevy Bolt cars sold, which is a lot of cars with potential issues. We reached out to GM for comment about the fires, but had yet to hear back at time of publication.

In the Bolt, the battery sits in` the back of the car along the floorbase, as seen in these diagrams from GM when the 2017 Bolt first launched. In one of the fiery battery incidents, the car owner reported smoke inhalation-related injuries. No other injuries or deaths were reported in connection with the car fires.

While electric vehicles are heavily scrutinized after reports of fire, gas-powered vehicles can also catch on fire while parked and unattended. Fires are often traced back to the electric motor and battery, but traditional internal-combustion engine vehicles also experience electric fires.

So far, the agency has not found a cause for the Bolts'``` electric fires during its preliminary evaluation. NHTSA will post any findings or next steps on its website, where Bolt owners can look up their vehicle for any reports, recalls, and investigations. If something serious and widespread is discovered, General Motors will also reach out to affected car owners. At the beginning of this year, Tesla and its electric vehicles were under investigation for sudden acceleration issues affecting 127 of its vehicles. That case is still open.

UPDATE: Oct. 15, 2020, 1:14 p.m. ET General Motors responded with a statement about the investigation:

"The safety of our products is the highest priority for the entire GM team.  We are cooperating with NHTSA in their investigation and we are conducting our own investigation into these complaints as well."