My first two years of college, I walked everywhere and rode the bus when I needed to. The last two years I owned a car. I remember trying to figure out which was cheaper. One way to determine that is to apply the IRS Standard Mileage rate.
This is the number that is intended to be a reasonable estimate of all the costs of driving a vehicle for one mile, including gas, oil, taxes, insurance, wear and tear, and repairs.
The press release for the 2007 rate is here. (To find the rate for other years, type the year and "Standard Mileage Rate" into the search box.) It's 48.5 cents per mile for 2007.
This means the cost for my commute is $7.20 a day. It costs $3.00 to take the bus to and from work.
That's the money part. But time equals money too. Let's look at that.
Well. I'd have to say at this point that my time is worth more than $3.15 an hour. Of course, there are other things to factor in. Perhaps that's time I could be entertained. Perhaps it's time I could use twice... say for reading and for commuting.
But looking at the trip planner, I realize there's another option. I could drive two miles to a park and ride and eliminate one of the buses. Let's look at that.
$4.20 an hour starts to get interesting. I mean, if you take my take-home pay and divide it by all the hours in a year, $4.20 looks pretty good. Especially if I fit in other things... like riding my bike for those 4 miles and getting exercise. Or riding my bike past the community garden, watering my plot, and then doing grocery shopping at the Asian market on the way home.
Maybe it's not literally cheaper, but perhaps it makes sense a couple times a week.