When we moved me and Lucia from Germany to UK, we drove a van, and I got a big dog crate so I could put Lucia's litter box and a lot of stuff that smelled like home in the box, and there would be enough air circulation. She was very good, some whinging and crying, but she slept a good deal of the time as well. The most worrying part was on the ferry, as they wouldn't let us stay in the van with her, but she was fine.