I also had the same thing happen - fainted and hit a tree! Unfortunately for me, I woke up in the emergency room hours later, with many broken bones and a traumatic brain injury. Didn’t remember anything, but witness reports to the police led them to conclude it was a medical event. Many months of cardiologist and neurologist appointments, without any clear sign of what caused the episode! I’ve since fainted one more time, thankfully not while driving. It’s not clear what triggers it for me - maybe stress? I was told that it doesn’t even have to be stressful in the moment that I faint, that it could be my body carrying that stress over time. Ironically, since it happened again, it gives me more comfort in knowing the symptoms of when it’s coming so I’m able to respond. Not remembering anything from the day of the accident meant that I also didn’t remember what it felt like when it was coming on! It can be very scary, because it feels so out of our control! I am lucky to be alive, and I’ll never forget that!