in my experience, they are just like children. The MORE you take them in a car, the MORE they get use to it.. and the younger you do it, easier it is for them to get use to it.
Just take your dog for a few short distance rides frequently and let him get used to it. Put him in the back seat with a rubber sheet covering the entire place. Ask your wife to get in the back with him and keep him accompanied. Open the window and make him look outside when travelling for the first few times.
Not a big issue... you just have to make your dog get use to the motion of the car.