How to Calm Claustrophobia in a Car?

the MRI thing, yes !! when i had one they asked if i'd like a towel over my eyes so i can't see the tight space i'm in and it really helps. you could get a sleep mask to wear over your eyes and just put some headphones in. do it as long as you can and maybe even fall asleep the whole time

looking out the window and focusing on the outside of the car helps me

It sounds silly and it’s not realistic for 5 hours straight but when I had an MRI I just closed my eyes really tight and imagined I wasn’t in such a small box lmao

Someone else recommended this to me; try box breathing. You basically just inhale, hold for 3-4 seconds, exhale, hold for 3-4 seconds and repeat. It’s actually helped me and I hope it helps you too