[Shotgun!]

3 days. There are the extras to think about; the tickets and insurance have to be paid before they'll tell you were the impound is.
A few years later I had the Saturn towed on me. That was all a mistake and the cop apologized, but it did take something like $220 to get it out. As for how long it had sat there that time; I was there with the money before the tow truck showed with my *wonderful plastic car*.

On the subject of how much money the tow yards are: The only laws governing them are to protect them, not the people they tow. They are within their "rights" to charge whatever they want. They can even change their rates on a "per account basis". One lot I was at (for a friend's car) showed me just how they do this very thing. I felt so bad for the owner of that 'vette...