You need to get him used to the car very gradually - pop him in the car with out the engine running for a 2-3 minutes at first once he is comfortable with that gradually build it up till he will eat his meal in the car. Then and only then try sitting in the car with him with the engine turned on only for a few minutes build up gradually to moving in the car but only move onto each step when he is comfortable with the last one. It may take a month or two to do it but you can make him a happy traveller with time and patience
If he is still car sick a little ginger biscuit may help or you can get tablets from the vet to help (but if you can avoid them it's better as they have a sedating effect).
In the house you need to treat him like a rescue dog
