We've all had this experience one time or another: you're late for an appointment and realize that your gas tank is running on empty, rather than taking the time to fill it up you just put enough to hold you over. For some of us this is more than just a rare occurrence, for some, this happens every time we visit the gas station.

So, are we saving more than just time when we only fill the tank part way or is it better to always fill your gas tank full each time we visit the pump?