Research shows that wearing your mask, and opening the front passenger window, and the window behind the driver seat helps to reduce the spread of the novel coronavirus in your vehicle. See this NY Times article.
I am interested in carpooling because flying, taking amtrak, or even greyhound, is too darn expensive. I will need at least 2 weeks notice to take off work for any trip. I am highly allergic to cats. I do not eat dairy at all, I read labels on everything. I can take turns driving, but prefer to not drive in big cities.