I traveled with my six cats when I moved from Connecticut to Michigan. (I've since moved back to CT). I didn't feed them after midnight before the trip. Although I DID keep water out. They all did great. Slept all the way. We're talking adult cats, not a baby kitty. I think your little one will do just fine. She'll probably sleep all the way as well.

4 hours isn't bad. My trip was 13 hours!! I drove straight through.