My daughter has been traveling five hours to and from her dad's house in the city for years. She uses a small litter box on the floor in the backseat (lined with a litter tray liner) with about three cups of litter in the tray. Her cat just lays on her bags, coat, pillow or whatever is handy while they are traveling. We've even taken her camping with us for up to two weeks at a time in the 5th wheel. Now that she's getting older (16) she tends to get motion sickness so we have to make sure her food and water were removed from her in the evening before her trip starts. So far so good. We also "dry lot" cattle before taking them to the livestock auction. It helps keep the trailer and the cattle a lot cleaner. Works the same for a cat.