Very much not an expert, but I have been around pet cats for the majority of my life and have one keeping me good company just now. They're very much high-strung creatures of habit; they don't like change, and they don't like situations they don't understand. Car trips are things that happen too rarely for them to be used to, which are noisy, which involve them being shut in a small box, and which mess with their balance because they have no idea why the ground keeps moving. It's really stressful and they don't know what to do about any of it, so they want your help