Someone should sit next to him and speak softly and comfort him in his cage.
Put clean bedding or his blanket inside that smells of him and home.
Cover the cage with a blanket or towel so he doesn’t have to be a scared of the scenery flying by or have direct sun on him.

Have at least hay inside with him; a litter box if you can and water is good too. If you can give him a break or two I’ve read the suggestion of stopping the car and letting them out on the backseat (think safety – block small spaces and don’t open the doors).

Hand fed treats occasionally from his travel companion would likely be appreciated too

My bun went on two 6 hour car rides with me with three months of no travel at all in between. He was fine!

Put in his litter tray and a lot of hay (if there is room, something soft to lie on as well) and some greens. Don’t bother with water because it will just spill. Cover at least the top of the cage so the sun can’t hit him, and also to block the view in case that’s a bother. I wedged mine’s carrier way in the back of the car (the only place I could get it secure). Bonus being it was furtherest from the engine and radio noise, but I could call back to him if I felt like a chat

When you do stop for a break put some water and more of his favourite greens in the cage to see if he’ll drink and eat – always offer water. My rabbit won’t go for it straight away; he’ll wait about 5 minutes after the car has stopped moving before tucking in, so give yours some time. I didn’t let mine out at all in the car because I was too worried i couldn’t get him back into the carrier. Just got it over an done with so I could get him home as quickly as possible.

2 hours isn’t too long, I’d only stop once if you need to. You’ll both be fine! good luck!