For Want of a Deal

I witnessed an act of stupidity yesterday as I filled up my gas tank.  Gas around here is in the $2.30 to $2.40 range and two stations that sit across from each other.  The price of regular at Sunoco is $2.399 while it's $2.369 at BP.  I watched a woman pull into the Sunoco, get out of the car and prepare to pump gas into her Ford Focus when she noticed the price difference across the street.  She put the pump handle back, got into her and drove across the street to fill up.  Seems reasonable, no?  She drove a Ford Focus, a car with a 12 gallon tank.  The price difference is 3-cents per gallon.  If her car was completely empty, running on fumes and sputtering to a halt, that would be a grand total savings on the fill-up of 36-cents.  I have watched other people (men and women both) do this same thing with 1 and 2-cent differences.  So when would you see a significant difference?  Think about it, even after 100 gallons, the savings would only be $3.00 and the gas would still cost $236.00.  So, is it really worth it to look for the absolute lowest price?  That's my opinion.