You open the car door and your puppy backs away. Maybe the only rides they have taken ended at the vet, or the moving floor simply feels strange. Driving around until they "get used to it" may expose them to more worry or nausea than they can handle. If you can practise before the next necessary trip, begin with the car parked.
Dogs Trust recommends starting with calm experiences near the vehicle, then introducing entry, engine sound and short journeys gradually. Safety still comes first: the puppy needs an appropriate secured travel space or fitted restraint. Check local rules and the vehicle setup. They must not roam near the driver or ride loose on someone's lap.
Step one: the car is just a place
Choose a quiet time and let the puppy look at the parked, switched-off car from a distance. Reward a calm glance or a voluntary step closer. Then walk away. Another day, let them sniff near the door. Don't lure them so far with food that they suddenly find themselves trapped when the treat is gone. Let them choose to retreat.
Once the outside is easy, practise entering the travel space without going anywhere. A familiar blanket may help, provided it does not interfere with safe restraint. Sit with them briefly, reward relaxed behavior, then leave. You may need to teach the crate or harness separately at home before it feels familiar in a car. Keep the car cool and do not leave the puppy alone there, even for a short errand.
Next, introduce the engine while the puppy is secured and a trusted person can observe if possible. Some puppies are fine with the sound but struggle with movement. Try a very short, gentle trip when the parked experience is comfortable. Choose a route you can end quickly and a calm destination, not a long journey you cannot interrupt.
Notice the kind of difficulty
A worried puppy may pant, freeze, scramble or refuse to approach the car. A carsick puppy may drool, repeatedly swallow or vomit. Some have both experiences. Tell your vet what happens and when: before entry, once the engine starts, only in motion, or after a certain length of time. Your vet can assess motion sickness and advise on a safe plan. Do not give a human anti-nausea drug without veterinary direction.
If your puppy is distressed, make the next session easier rather than increasing the distance. If vomiting occurs or they seem unwell beyond the trip, contact a vet. A needed medical appointment still needs to happen, tell the clinic about the travel problem so they can help you plan it.
The common shortcuts that backfire
Forcing a puppy into the car and immediately driving for an hour makes the car a predictor of being trapped. Offering a pile of treats while ignoring their body language can do the same. So can practising only when you have a deadline. Reserve a few sessions when you can leave after a minute.
Do not let the puppy climb or jump out the moment the door opens. Make sure you have control of them before opening it fully, especially near traffic. Use a secure, comfortable travel setup every time, including on the shortest drive. A trip that goes well is not a reason to remove restraint.
For today, the entire lesson can be walking toward the parked car, rewarding one calm sniff and going home. There is no mileage target. The next ride becomes easier because the car has stopped being one enormous surprise. Once the car is safely set up and sickness is considered, the dog handling and reward-timing guide can help you reward calm choices near a parked car. Driving farther is not the lesson.
Sources: Dogs Trust, "How to train your dog to travel in the car": https://www.dogstrust.org.uk/dog-advice/training/outdoors/car-travel . VCA Animal Hospitals, "Road Trips and Car Travel With Your Dog": https://vcahospitals.com/know-your-pet/road-trips-and-car-travel-with-your-dog.