How can I ensure a comfortable and safe 20-hour car ride with my cat?

To ensure a comfortable and safe 20-hour car ride with your cat, make sure to provide a secure and well-ventilated carrier with familiar bedding, food, and water. Take breaks every few hours to allow your cat to stretch, use the litter box, and drink water. Avoid feeding your cat right before the trip to prevent motion sickness. Additionally, consider consulting with your veterinarian for any specific recommendations or medications to help keep your cat calm during the journey.