I drive. I love it when they sit up front and invite them to do so. I can tell a lot about them by where they sit, as well as how they view me.
When they sit in the back, alone, I am just their personal driver. It's rare to have really good conversations from the back seat. When they sit up front, I'm a friend with a car. See what I did there? There are usually great conversations about things we love about our town, life, kids, school, everything. For those that say, "I don't pay my friends to drive me," would you really call a friend to come pick you up from somewhere they weren't already to take you somewhere else and not chip in?