In mid-April, a Tesla crashed into a tree in a suburb outside of Houston, and it took firefighters four hours to put out flames fueled by the car's battery pack. When the fire was out, they concluded that neither of the car's two occupants had been in the driver's seat at the time of the crash. A Tesla executive later broke with that official account and claimed that a person had been in the driver's seat. A National Transportation Safety Board spokesman later said Tesla was "working with" the investigation but is "not a party" to it, a break with typical procedure that suggests a strained relationship between Tesla and regulators.

Federal safety regulators are sending a team to California to investigate a fatal freeway crash involving a Tesla, just after authorities near Oakland arrested a man in another Tesla rolling down a freeway with no one behind the steering wheel. Experts say both cases raise pressure on the National Highway Traffic Safety Administration to take action on Tesla's partially automated driving system called Autopilot, which has been involved in multiple crashes that have resulted in at least three U.S. deaths. The probe of the May 5 crash in Fontana, California, east of Los Angeles, is the 29th case involving a Tesla that the agency has responded to. "The details of whether the Tesla was in autonomous mode are still under investigation," Officer Stephen Rawls, a spokesperson for the California Highway Patrol, said in an email Wednesday. The Tesla driver, a 35-year-old man whose name has not been released, was killed and another man was seriously injured when the electric car struck an overturned semi on a freeway.

The Model X electric, sport-utility vehicle accelerated in the final seconds to about 71 miles an hour before the March 23 crash in Mountain View, Calif., according to a preliminary report from the National Transportation Safety Board. The report comes as auto makers and Silicon Valley are testing technologies that allow for varying levels of automation behind the wheel. Those include systems with driver-assist features as well as those that enable fully self-driving vehicles. Fatal crashes have fueled concerns about whether driverless technology is ready for the real world. A Tesla spokeswoman pointed to a previous company blog post about the incident that touted the safety of its vehicles.

The Tesla Autopilot system was engaged when a Tesla Model S sedan was crushed as it rammed into a stopped truck at 60 MPH in Utah last week, the driver has told police. The driver luckily escaped with only a broken foot, though the car suffered extensive damage. When interviewed by police, the Tesla's 28-year-old driver "said that she had been using the'Autopilot' feature," and was looking at her phone shortly before the accident in South Jordan, near Salt Lake City, according to a statement Monday from South Jordan Police Sgt. Winkler told The Deseret News that the diver, who hasn't been identified by police, had entered an address into the car's GPS and was looking on her phone for possible alternate routes. She "looked up just as the accident was about to happen," he said.