Most dogs are not bad in the car. Most dogs are loose in the car, which looks the same from the driver's seat. A dog that can move between the front and the back will move between the front and the back, and once it has done that a few times it has learned that the car is a place where it paces.
Fix the space first and the behavior usually follows. Three things do most of the work: a boundary, a surface, and water.
1. A boundary, so the dog has one place to be
This is the change that makes the biggest difference to a nervous dog, and it is the one people skip because it sounds like the fussiest.
An elastic barrier net stretches between the front seat backs and stops the dog coming forward. It takes a minute to fit, it comes out when you do not need it, and it means the dog stops trying and settles. If your dog travels in the footwell or across the rear bench, a folding pet fence does a similar job for a wagon or a hatchback.
For a cat, the boundary is a carrier and there is no substitute. A foldable clear carrier keeps a cat where it can see out, which is the part that keeps most cats quiet, and it folds flat between trips instead of taking up a cupboard.
2. A surface that is easier than the seat
A leather or fabric seat is slippery, and a dog braced against a corner all the way to the coast will arrive tired and stressed. Give it something that grips.
A mesh window seat hammock slings between the front and rear headrests and makes a flat, contained bed out of the rear footwell and bench. The dog cannot roll into the footwell, and the mesh window means you can see it. For an older dog or a dog with joints to think about, a hard-bottom seat extender fills the footwell so the whole back becomes one level platform.
If you would rather keep the seat as it is, a waterproof seat pad is the low-effort version: it catches the mud, the hair and the wet, and it goes in the wash. A pair of door protectors covers the other place claws land, which is the inside of the door on the way in and out.
3. Water, without a wet floor
Dogs pant in cars, and a panting dog dehydrates faster than a walking one. The problem has never been remembering the water, it has been carrying it.
A travel water and food bottle pours into its own bowl and pours the rest back into the bottle, so nothing gets tipped into the trunk. A collapsible double bowl covers food as well on a longer trip. Offer water at every stop even if the dog refuses it. Refusing is fine. Not being offered is not.
Building the drive itself
Kit fixes the space. The rest is the routine.
Empty the dog first. A walk before you load up, not after. A dog that has run for twenty minutes sleeps for two hours.
Feed early or not at all. Two to three hours before you leave, or wait until you arrive.
Stop every two hours. Lead on before the door opens, every single time, without exception.
Air, not aircon, at the start. A slightly cool car is easier on a panting dog than a cold one.
Practice short. If the car currently means the vet, drive five minutes to a field and come back. Do that four times and the car means the field.
If the anxiety is the problem, not the space
Some dogs and cats are genuinely anxious travelers, and no hammock fixes that on its own. A calming comfort spray on the bedding twenty minutes before you set off, or a calming vest for a dog that responds to pressure, are both worth trying alongside the short practice drives rather than instead of them. If your animal drools heavily, vomits on every trip or panics, talk to your vet before a long journey. There are things they can prescribe that we cannot sell.
The rest of the kit is in travel and car.
