Zip code distance calculator WAY off sometimes.
 

I've noticed this distance display being off every now and again, but this time I took notes.

I have three images attached. The user who posted this ad is located in Michigan with zip code 49320. I am located near Tallahassee, Florida at zip code 32399. According to the zip code calculator, Michigan is only 110 miles from Tallahassee, FL. I find this a little hard to believe. The last time I drove up to Chicago, which is closer then Michigan to me, it took me 22 hours. I am fairly certain I was driving more then 5 miles per hour that trip. :)

I will default to Michael on that one since he wrote the zipcode mod ;)

We rely on the data in a free database provided by the US Government, we don't maintain the data or have a way to correct what may be wrong (would mean having access to some other source for zip code with longitude and latitude information).

If you need more exact information, I would recommend purchasing a commerically maintained database, like the ones at http://www.zip-codes-latitude-longitude.com/