It’s the kind of blaze that veteran Chief Palmer Buck of The Woodlands Township Fire Department in suburban Houston compared to “a trick birthday candle.” On April 17, when firefighters responded to a 911 call at around 9:30 p.m., they came upon a Tesla Model S that had crashed, killing two people, and was now on fire. They extinguished it, but then a small flare shot out of the bottom of the charred hulk. Firefighters quickly put out those flames. Not long after, the car reignited for a third time. “What the heck? How do we make this stop?’” Buck...