I get derealization when highly stressed. Not often, but enough to be frightened and concerned. I become unaware of my surroundings, and it can hit me out of nowhere. I hate when it happens when around others, because I have been judged, called absent-minded, when it was a scary experience for me. Although in general I am not the best person when it comes to being aware of my surroundings, sometimes it's almost a dream-like state and things seem confusing around me. I can also relate to the car-related experience that you had.

Other times, I'll get dissociation/possible depersonalization, where I feel detached from my body, but feel trapped in a past moment or experience. When I come back inside my body, I start crying or experience a panic attack. I don't have PTSD. I do know complex trauma can sometimes be the route of some of these things, as I learned in Psychology, but my experiences seemed different than that, although very unpleasant, scary, confusing, uncomfortable, etc. I don't experience this often, but the times where I have experienced this has been alarming.