A Tesla Model S electric car caught fire this week after hitting road debris on a Tennessee freeway, the third fire in a Model S in the past five weeks.
The blaze on Wednesday afternoon near Smyrna, Tenn., engulfed the front of the car. A spokeswoman for the Tennessee Highway Patrol says the Model S ran over a tow hitch, which hit the undercarriage of the car, causing an electrical fire and "extensive damage" to the car.
The Model S undercarriage has armor plating that protects a battery pack of lithium-ion cells. Tesla said it did not yet know whether the fire involved the car's battery. Experts say that if debris punctures the shield and damages the battery, it can cause shorts and arcing that can touch off fires.
Company spokeswoman Liz Jarvis-Shean says the fire was not spontaneous. She says Tesla contacted the driver, who the company said believes the car saved his life. Tesla CEO Elon Musk has said that the design of the Model S is safer than that of a car with a conventional fuel tank.
It's the second Model S blaze involving road debris. In early October, a driver near Seattle hit debris that pierced a shield and the battery pack, causing a fire. In the other fire, a driver in Mexico crashed into a concrete wall and a tree at a high speed.
The National Highway Traffic Safety Administration, the U.S. government's auto safety watchdog, says the agency will contact Tennessee authorities to determine if there are safety problems that need further action. NHTSA decided last month not to investigate the Seattle-area fire, saying there was no evidence it was caused by a safety defect.
While none of the drivers in any of the Tesla accidents were injured, the glaring headlines about fires were unwelcome for a company whose stock soared sixfold in the first nine months of the year. Since the first fire, Tesla's shares have lost more than 27 percent, and this week's declines are the worst one-week drop since May 2012.
"For a company with a stock price based as much or more on image than financials, those recurring headlines are highly damaging," Kelley Blue Book senior analyst Karl Brauer said.
According to the U.S. Fire Administration, there are about 194,000 vehicle fires on U.S. roads each year. The vast majority -— 61 percent — start in the engine area, while 15 percent start in the passenger area.
Approximately 300 people die and 1,250 are injured in U.S. vehicle fires each year. Most happen in gas-powered cars, which make up the vast majority of cars on U.S. roads. Electric vehicles make up less than 1 percent of the cars sold in the U.S.
General Motors and Nissan make the top-selling electric cars in the nation, the Volt and Leaf.
A Volt caught fire two years ago after a federal crash test, but the government closed an investigation into the incident after GM agreed to a safety campaign to bolster shielding around the battery.
GM has sold more than 50,000 Volts in the U.S. since late 2010. Nissan has sold almost 38,000 Leafs. Tesla has sold an estimated 16,251 Model S cars in the U.S., according to Autodata Corp.
The Model S, which starts at $70,000, can go up to 265 miles on a single charge.
Al Jazeera and wire services