It's important to make your pet comfortable for your road trip. Just like you wouldn't want to be stuck somewhere you aren't comfy, neither will your pet. If you have an SUV with a pet barrier, bring along your pet's bed from home for it to lie on. If you don't have a barrier, bring your pet's crate and allow it to spend time in there. Dogs that are crate trained will appreciate the comforts of their own little house on the road. Cats are typically not crate trained, but they'll also prefer the security that a crate provides. Your pets like boundaries and tend to do better when confined. It's also unsafe to have your cat roaming around inside your car.
If your dog or cat doesn't have a pet bed, your favorite sweatshirt that you've recently worn should serve as comfy bedding. This provides them with some security. Any kind of blankets that your pet uses at home should be put in the car or crate as well. The idea is to make the vehicle as much like their real home as possible. While this may not exactly entertain them, it makes them happier. And a happy pet on a long trip makes a happy pet owner.