Rather than post more of the same, I’ll approach it from a safety angle.
A little preparation and forethought can go a long way.
Make sure your dog is microchipped and has a collar on with contact information, in case it somehow, worst case scenario, gets lost. I’ve met and read stories about people who were separated their dogs at a rest stop when it ran away, or after an accident, etc. Dogs can get scared in unfamiliar or sudden circumstances, and bolt. If you take the dog out of the car, make sure the leash is secure. Keep it away from other dogs, who may also be scared. And keep a good picture of the dog on hand in case you do get separated and have to do a “Lost” posting (for which there are specific networks, I believe; thankfully have never had to use any, but good to know they’re there).
Also make sure your dog is up to date on vaccinations, including bordatella (kennel cough) as it could pick something up at the dog areas in rest stops or other walking areas, or drink out of a dirty puddle, etc. If you suddenly have to use a kennel (which we had to once on a trip) some may require vaccination records. Or if you have to take the dog to the vet it’s good to have a printout or picture of a printout in case your own vet is closed. Also make sure they have flea and tick preventative as some areas may have these that your own area doesn’t.
Make sure the dog has plenty of water. Be careful with food - stick as much as you can to home food as the stress of the trip can cause tummy problems. Our dog travels pretty well but still gets slightly anxious in hotel rooms. Dogs are creatures of habit and even though they’re with their people, they don’t always like the disruption of their routine. This was just our experience, but our dog did better if we didn’t go back in the room after we left (for a reasonable time, like a few hours, not all day). Once DS forgot something and had to go back, and that caused the dog to bark, thinking it would get him back again, and that caused a problem. So before you leave the room, make sure you have everything you need. We did use a crate, as well.
And of course the biggie is not leaving the dog in a hot car. Temperatures can soar inside in minutes, and as a pp mentioned, it could be a problem. If we find ourselves in those circumstances, one of us usually stays in the car with the dog with the AC on while others go inside somewhere, and we switch off. It takes a little longer but it’s better that way. I wouldn’t leave the dog alone with the car running. Dog theft is also a big problem now as dogs became scarce during the pandemic. Your dog is worth a lot of money to someone who has bad intentions, so protect your dog at all times.