Yes indeedy, that is a most excellent thing to do.
Singing in the car, really belting it out at the top of your lungs, is one of the things I just love love love about driving. Even better if someone has made you a playlist or given you a bunch of CDs with excellent songs on them (Thank you, Bruddah!). And, you know that moment when you’re driving in the car with someone and you realize that you’re both singing along? I love that moment. That is a good friend.
And, when you can sing with someone and have comfortable silence? Definite keeper category.