With today being the biggest travel day of the year, I want to solicit some opinions. Years ago, a friend suggested to me that I use the IRS’s mileage cost guidelines in determining the costs of travel by car. Currently that’s 50 cents a mile.

Using this rate often puts me at odds with people around me when discussing trips because they merely talk about gasoline costs. There’s a wide discrepancy between the two.

This mainly comes up when discussing long trips. They’ll say, for example, I’m going to drive to Tulsa because I want to save money. From Abilene, that’s roughly 400 miles, so just the trip should cost $400 roundtrip. Flying from Abilene to Tulsa currently costs about $200.

There are other considerations, of course, like transportation once you arrive, how many people are making the trip, etc. However I once heard someone say that if the trip is over 300 miles, flying is cheaper. That seems about right.

Another possibility is to rent a car. This is typically much cheaper than using your own car, unless you like to give money to the rental car agencies by buying the insurance they offer. In almost every case, the insurance you have on your car will also cover your rental (but ask your agent first!).

Anyway, what I’d like to know is if using the IRS mileage rates is legit. Or how should one calculate these costs?