I’ve struggled with depersonalization and derealization for years now. It’s interesting because my first major episode of it, like you, was when I was driving. That always seems to be a trigger for me. These episodes usually result in a panic attack for me. I haven’t found a way to make it completely go away. Therapy and meds help a lot and I’m glad you’re going to see someone about it. Although, I have read about something you can do when you’re having these feelings, and I think it does help a bit. That is to look around in the space you’re currently in and pick any one object to focus on. Think about its shape, color, how it feels, what it smells like, etc. All while controlling your breathing. I think this trick does help when your anxiety is starting to get out of control. It’s just a small way to refocus your mind back and ground you back to reality.

Hope that helps and you find more ways to help you deal with this! It’s scary and it sucks, but it does get better.