Good movie!
I really liked the overall concept and I think you really managed to create the right mood.
Beside that I think you could improve these things:
1) I think the animal or fox or what it was was not appropriate for the story. Too cute. And mixing this thing with a human boy was kinda strange.
2) A Narrators voice would have been cool
3) The driving sounds were not appropriate. The sound was the one of passing by cars and not of a car going down a road alone.