Turning car rides into a normal, calm part of life instead of something only associated with the vet.
If the only car rides a puppy takes are to the vet, the car itself can start to predict something stressful. A few short, low-stakes rides early on — around the block, to a nice park — build a different, calmer association.
For a puppy who seems unsure about the car at all, begin with the engine off — sit inside together, offer treats, let them explore the seat or carrier. There's no need to actually drive anywhere for the first session or two. If your puppy won't go near the car at all, see what to do if your puppy is scared of the car.
Once your puppy is relaxed in the parked car, sit together for a short while with the engine running, offer treats, then switch it off. Keep it brief, and stop before your puppy looks worried. Only do this outdoors, never in a closed garage.
Use a crate, carrier, or harness-based seatbelt attachment appropriate for your puppy's size — loose in the car isn't safe for them or for you. A familiar blanket or toy in the space can help it feel less foreign. Never leave your puppy alone in a parked car, even for a few minutes.
A five-minute drive to somewhere pleasant is more useful early on than a long trip. Watch for drooling, whining, or stillness that suggests carsickness — if it shows up, shorter, more frequent trips usually help more than pushing through longer ones. If your puppy vomits repeatedly, is sick on most trips, or vomits when they're not travelling, contact your vet.
As short trips go well, gradually extend the distance and vary the destination so the car doesn't come to predict any one specific place. By the time a longer trip or a vet visit is necessary, the car ride itself is no longer the hard part.