When I was doing my driving test last year the instructor asked if I would prefer he not talk or if I liked conversation. I asked him to chat with me as it helped me feel less nervous.
Now it depends who's in the car. If its just me and the kids we sing if I have another passenger we talk. If I'm by myself I sing along to my LOUD music and argue with the navman (even if I don't need his directions, I feel less lonely ;p).
*the bass, the rock, the mic, the treble, I like my coffee black just like my metal*