If you have a dog that is either too big to pick up, doesn't like being picked up and will bite or you just want to make your dog more comfortable with getting in the car then this is for you. It all starts off with hand targeting. (Pardon the old video.) Once your dog can successfully and reliably target your hand then you're ready to start the process of getting him comfortable with jumping in the car.
Step 1: Get him comfortable with being around the car
Practice hand targets around the car. Be very unpredictable with these targets so he doesn't catch on to a pattern. Flirt with the line that he will not cross. Always let him vote with his feet and don't try to get him to cross that line until he is ready. Make sure that leash is loose!
Step 2: Get that line closer to the car
As he continues to get more comfortable he will target your hand closer and closer to the car. Do this and as always allow him to vote with his feet. Keep your hand still once you've presented it and happy talk him if he's contemplating whether or not to do it.
Step 3: Place your hand above the bumper
Once he is comfortable and not showing any stress signs when you're asking him to approach the car you're ready to place your hand above the bumper so he has to target it partially within the car. Keep the same pattern going. Some in this position, some away from the car. You should see him get more and more comfortable with this.
Step 4: Place your hand in the car so he has to step up
Get splitty here if needed. Keep your target hand steady and reward him if he touches it. If he is struggling a bit with this, look for any small version of the behavior you can reward. Do that and then invite him away. Repeat until he is stepping up onto the car for the target/reward. Repeat, repeat, repeat!
Step 5: Ask him to get all the way in
There is no rule for how long each step will take. And there may be splits in between these steps that you'll need to add in. But the final step is getting your dog to jump all the way in to target and then giving a jackpot of food rewards. It helps to get a little momentum like I show towards the end of the video.
Remember to be patient, have fun and let your dog vote with his feet. Sometimes this takes 10 minutes to accomplish while other times it takes multiple hour long sessions. Also, make sure your car rides aren't always a predictor of something your dog dislikes. Getting in the car and going to the drive through once per week for a snack will help keep your dog happy about getting in the car. Below is the video!