Awww.... he will be ok, it just takes time for them to get used to the car. Maybe you can create some distractions like give him a toy, play with him in the car, or even treats (as long as he doesn't get car sick, which seems to happen the first few times they are in the car... but it usually goes away quite quickly).
Don't be tempted to avoid car trips altogether though - it's better to expose him to the car as normal and let him get over it. It will happen!
Good luck
