You know what is depressing, though? This equation doesn't work out for me. When I was riding my bike to the grocery store, I always wound up starving and thirsty (even if I brought water with me) and bought a water and a Luna bar along with my groceries ... which cost me more than the gas to drive there would have. Even when I drive to work, my commute is so short that I only have to fill my gas tank every couple of months. When I am riding to work there is always some little thing that the bike needs, or that I justify buying because I'm riding to work. (Let's not discuss the number of messenger bags I own.) Walking should be free, but I spend less on gas than I've spent on good walking shoes that I justified because, you know, my feet are my commute vehicle. I am the Imelda Marcos of sensible walking shoes.

My car is paid for and under warranty, so the only maintenance costs I pay for are oil changes and tire rotations, and I need those very rarely because I drive less than 3,000 miles a year. Even if I walk and bike enough to drop that down to 1,500-2,000 miles a year, it is cheaper for me to drive most places than it winds up being to walk or bike. And the bus is always the most expensive option except on those rare occasions when I have to pay for parking (and then I am usually with my husband, so you double the bus fare and suddenly parking is a bargain).

I think it is just too cheap to drive.