A Tesla Model S electric performance car caught fire Wednesday outside Nashville, Tenn.  The driver walked away unharmed.

It is the third fire of a high-priced Model S in six weeks. On Oct. 1, a Model S outside Seattle caught fire after it collided with a large hunk of metal believed to have fallen off of a truck. On Oct. 18, in Merida, Mexico, a driver who was reportedly going 100 mph into a roundabout, went airborne, sheared 17 feet of concrete wall, according to Tesla CEO Elon Musk, then went through a concrete wall and smashed into a tree.

In all three cases the drivers walked away from the accident unharmed. Tesla backers use this as proof of the 4,600-pound car’s safety; it earned five stars from the National Highway Transportation Safety Administration earlier this year, among other top accolades from Consumer Reports and Motor Trend.

Plug-in Cars reports the accident outside of Nashville is consistent with the road-debris-caused fire outside of Seattle. In both cases, the car detected a fire and instructed the driver to pull over. The most recent fire is believed to have been caused by the driver hitting a trailer hitch, according to Charles Cooper for CNET. It sounds as if the hitch was laying in the road and not caused by the Model S rear-ending a vehicle with a hitch. 

Images posted on Twitter and the Tesla Motors Club forum show firefighters dousing the front of a charred Model S. Some Tesla owners on the forum are speculating if there is a problem with the latest iteration and most high-powered and high-priced Model S trim, the P85+.

Tesla is sending a team to investigate, according to a Tesla spokesperson, who added that the driver was not injured and believed the car saved his life.

The fire happened near the exit for Smyrna, Tennessee, home of the Nissan Leaf factory. The Leaf is an economical electric car that has not had any problems with fire.

Fuel tank fire is common in gasoline powered cars, according to David Herron for Plug-in Cars. There is an average of 152,300 automobile fires a year, according to the National Fire Protection Association. After the Washington fire, Tesla claimed its massive battery pack is safer than fuel tanks. Plug-in Cars reports that the battery pack, which extends between the wheelbase under the car, is protected by a quarter-inch aluminum plate and divided into 16 modules with built-in fire-resistant barriers. The battery pack is designed to push flames to the front of the car.

The Washington fire was exceptional, prompting the NHTSA to conclude it was an accident, not a vehicle defect; the Mexico fire was driver error; the latest fire may intensify scrutiny of the Model S, which went on sale in June 2012 at a price that ranges from $70,000 to $120,000.

Tesla stock had dropped 15 percent on Monday after third-quarter sales didn’t meet analysts’ expectations, which Musk said might have been overvalued. Share price had risen over 400 percent this year, from $35 in mid-March to over $193 in late September. October was a lone down month for Tesla this year. As of this writing, TSLA is trading at $140.

rduffer@tribune.com

Twitter  @DufferRobert