Tesla CEO Elon Musk noted in the post that "you are five times more likely to experience a fire in a conventional gasoline car than a Tesla!"
According to Musk, a large piece of curved metal fell off a tractor-trailer rig. Theoverran the object, causing it to lever up into the bottom of the car with a force of 25 tons.
The metal object created a 3-inch hole in protective plating underneath the car, breaching one of the 16 battery compartments in the chassis. The intrusion caused the battery pack to catch fire, although firewalls between the battery modules and in the structure of the car prevented the flames from moving into the passenger compartment.
Musk points out that internal combustion cars have much less protection in the chassis than does the Model S, so this type of accident could have been much worse. Citing the National Fire Protection Association, he writes that there are 150,000 vehicle fires every year.