I always rent a car at the airport from 14CARS.com. And I can give a couple of tips on how to make a trip for a pet by car more comfortable:
1. Feed the animal 8 hours before the trip. Only water can be left in the bowl for the journey. 2. During the trip, the pet can get sick, so take a first aid kit for him with you. 3. Walk your pet before the trip. And when you stop, walk him too.