I usually don't feel too bad for rabbits. We seem to have plenty of them.
When I was a kid, my dad came home from work with a rabbit. He had taken my sister with him to visit a member of his church (Dad was a preacher FYI) who was sick and not doing well, and they had a farm.
The ladies daughter took my youngest sis out to see the animals in the barn and in the end we got a pet rabbit.
It was pretty cool, My dad built an "Inside-outside" cage for it, meaning half the cage was inside with a little flap door so it could go outside to get fresh air whenever it wanted to... it was a really sweet animal, she would nuzzle up against you if you held her and I don't remember her ever biting anyone.
Anyway, cut to that winter around November sometime, it didn't snow, But the temperature dropped quite low one evening. We had a dog in the barn also who did just fine, But for some reason the rabbit saw fit to trash its bedding (Straw, Helps them keep warm) and when we went down to visit the next day with my sister and my little cousin (Girl, same age as sis, around 7-8 years old) we find "Thumper" just chilling in her cage.
I say "CHILLING" because she was frozen solid...
As a F'd up kid I thought it was quite funny, My cousin cried my sister was upset but shed no tears...
We buried her a few days later.
Thinking about it now, It must have been a horrifying way to die...
I think in comparison, Your Road Trip'd bunny probably died in a much quicker and less horrifying way.