On March 26, 2014, the US Department of Transportation’s National Highway Traffic Safety Administration (NHTSA) published conclusions of their investigation into two incidents of Model S vehicle fires related to road debris.
Neither incident resulted in injuries though both vehicles were destroyed by the fires which began when road debris managed to puncture the aluminum battery pans encasing the battery array housed in the bottom of the chassis. The report concluded that “impacts with road debris are normal and foreseeable” dismissing the allegation that the incidents involving road debris penetration of the batteries and enclosure components formed a defect trend.
As part of their own mitigation strategy, Tesla updated their software in November 2013 to modify the ride height at higher speeds. Earlier this month, Tesla announced that the Model S is now being outfitted with a triple underbody shield comprised of a titanium plate sandwiched between two specially engineered layers of aluminum designed to absorb, deflect and neutralize offending debris. The triple shield is also being offered as a free retrofit for all current Model S owners.