Drying herbs in your car is one of the easiest ways to prevent them from molding in the process. You can lay them out on newspapers, or put them in a paper bag on the front seat. The sun will cook them in a few hours and your car will smell wonderful. (However, now that I've moved to Texas, I’m slowly learning that it might be closer to a few minutes in this Texas heat!)
A simple way to replicate that fresh scent of herbs without butchering your entire plant is to crush a few leaves, stick them in a tea infuser and hang from your rearview mirror. You have a simple air freshener that smells better and is cheaper than those clunky cardboard ones; one that is greener for the environment and looks pretty cool, too.