ABSOLUTELY RIGHT!
We had the best time coloring Disney princess pictures, exchanging iPods, karaoke-ing along with the radio, and of course, using each other as pillows. One thing I've noticed as we've gotten older is that we give the driver a lot more respect than we did in high school. We keep each other in check to keep the volume down and the guy in the front seat knows that he may have to be navigator rather than Britney Spears superstar lip-syncher.
Road trips can be even more fun than your destination if you have the right attitude. Keep it safe, keep it fun!