If you plan on another long trip, try this before. This will take a bit of consistancy on your part. Take you dog on short trips. First around the block. Do that a couple three times a day for a week, then make the trips longer and longer. This allows your dog to get used to being in the car for longer and longer periods. Eventually and hopefully this will get your dog used to being put in the car. Leaving a familiar environment can be taxing on a dog and can cause them some stress. Training your dog to take a car ride and eventually it will return home can take some time, or they will get the hint right away. Depends on the dog. Talk to your dog while on the trip. Positive re-enforcement is the key to any canine training. Give lots of praise when they get into the car, while driving, again if you stop and start, and when ending the trip. Do this no matter how long or short the trip is.