Most likely scenarios: -Driver stopped himself due to medical reason (driver was 74). -Car's power-train issue caused it to stop. Less likely in dual-motor co

Most likely scenarios: -Driver stopped himself due to medical reason (driver was 74). -Car's power-train issue caused it to stop. Less likely in dual-motor configuration. Even less likely to happen suddenly. -Autopilot was on and driver fell asleep - Autopilot is programmed to come to a stop if driver input is not detected. Because it's Tesla there's great deal of attention given to Autopilot but in this circumstance, where car stopped completely, driver most likely have been unable to make the car go (for medical or technical reasons).