J.C.
I always sing to my children in the car. It feels a little funny when they are so young, but the more you sing the more he will be lulled by your voice. I used to sing, "If you're happy and you know it" to my daughter every time she started to cry in the car and she always stopped. I mean always!
I also have a sample cd from the music program, "Music Together" and my children love that one. It actually has a song on it about riding in the car and they make silly noises in the song. It is really fun and worth the money.