What does your commute cost you?

On the city of Fresno Web site, there is a commute calculator, where you can figure out how much your daily commute costs you if you drive alone to work. I put in the numbers for my 23-mile round-trip, driving my Prius, which gets much better gas mileage than our other vehicle, and came up with a daily cost of $14.73, or $3,713 per year.