A man I know drove into the back of a stationary car at about twenty-five miles an hour. Everyone walked away. The dog, who had been asleep on the back seat, did not stop at the back seat.
She survived. He does not talk about it much.
Here is the arithmetic nobody wants to do: in a 30mph crash, a 30lb dog becomes roughly a 900lb projectile. That is lethal for the dog and for whoever is in front of them. Short of a crash, a loose dog in the footwell can jam your pedals; a loose dog in your lap turns a swerve into a collision. And after a crash, a frightened loose dog bolts from the car into traffic — which is grimly common and is how a survivable accident becomes a fatal one.
Six things, in order of how much they matter.
1. Restraint. Any restraint. This is not optional.
The realistic options, best first:

- A crash-tested harness clipped to the seatbelt. The best balance of safety and practicality for most dogs.
- A secured crate. A foldable travel crate is the strongest option for a dog who settles better enclosed — but an unsecured crate is a projectile too. Strap it down.
- A boosted, tethered seat for small dogs (below). The full dog travel and car safety range sits together.
And the thing most people get wrong: clip the tether to a harness, never a collar. In a sudden stop, a tether on a collar applies the dog's entire bodyweight to their throat. This is not fussiness. It is the difference between a bruise and a crushed windpipe.
2. A booster seat — for small dogs, this is both safety and sanity
A raised booster seat does two jobs at once. It contains a small dog so they are not sliding across the seat on every corner, and it lifts them to window height — which matters more than you would think.

A great many "anxious" car dogs are simply carsick, and a dog who can see the horizon gets far less motion sick than one at footwell level watching the world blur sideways. It is the same reason you put a queasy child in the front. The tell is drooling: ropes of saliva before you have left the street is nausea, not fear.
3. A console seat — for the dog who needs to be near you
For a velcro dog, a console seat between the front seats is worth more than any calming spray on the market. High, forward-facing, and within touching distance of the driver.

Who it is not for: anything above small. And never on a seat with an active airbag.
4. A ramp — the one that protects them for years
Jumping down from an back of an SUV is a hard landing absorbed by the front legs, repeated hundreds of times a year. It is one of the quiet contributors to elbow and shoulder arthritis in big dogs, and it is entirely avoidable.

A folding car ramp is maintenance, not luxury, for any large dog and any dog over about seven. Introduce it before they need it — a dog already in pain will not learn a new skill. More in the senior-dog list.
5. A washable bed — because settled dogs travel better
Dogs settle on a surface that smells of home and does not slide. A washable car bed with a harness clip gives them a defined place, which is most of what "settle" means to a dog, and it stops the skidding on corners that keeps a nervous dog on its feet the whole journey.

It also keeps the mud off your upholstery. That is not a safety benefit, but it is the one you will notice every week.
6. A tracker, for the moment it goes wrong
The moment a dog is most likely to be lost is the moment a car door opens somewhere unfamiliar — a service station, a trailhead, a friend's driveway.

A reflective collar with an AirTag holder costs very little and turns a catastrophe into an inconvenience. Reflective is a bonus the first time you are looking for a dark dog at dusk.
What to skip
- The zip-line tether alone. It stops them roaming the car. It does nothing in a crash.
- A crate that is not strapped down. You have built a heavier projectile.
- Feeding a full meal before a drive. Two hours clear. This alone fixes a lot of "car anxiety".
- Head out of the window. Grit, insects and debris at 40mph, straight into an eye. Crack the window; do not hand them the view.
The one worth asking your vet about
If your dog is genuinely, miserably carsick, there is a licensed anti-nausea drug for dogs (maropitant). It is remarkably effective, and it is the single thing most owners do not know exists — they spend years managing an "anxiety" problem that was a nausea problem all along.
The full behavioral picture is in the calm car ride guide.
More reading: calm car rides with dogs · what helps an older dog