I mentioned yesterday that I had night terrors when I was a kid. If that is what she is experiencing, she will wake up and be very scared. And not understand what is going on, it's just a very deep feeling of fear and dread and panic. For me it was like I woke up but was still dreaming, so what I was dreaming was right there in the room with me.
For a kid it's truly terrifying.
I don't know if it's possible for you to do, but one thing that helped me was to go to another room and go to bed there. That helped a little because I connected the fear with the room I was in. The scary things were in that room. So staying in that room and going back to bed there was very unpleasant. I just really wanted to get away from it. You mentioned that car rides calmed her down, that makes sense if it's night terrors, leaving the room and building would be calming. Getting away from the scary things.
The good news is that it's something people grow out of, it's going on for a while and then it usually stops.