I've wondered the same thing for years. I'm always amazed when I I see people pull into a Mobil station near my home where the prices are usually 10-20 cents a gallon higher than any other station in the area, with Arco or Costco being at the low end. They're about 4 blocks from the nearest ARCO. And based on my one experience with getting a tire patched when I first moved to the neighborhood, their repair prices are high, too.

I find ARCO to be a pain because they don't take credit cards and charge a fee to use an ATM card which adds about 3 cents a gallon to their prices but that's nowhere near the amounts you mentioned on the price differential.

I think I've seen some credit card offers that have a "rebate" of about 4% on Shell gas. Other cards have smaller rebates on purchases which are doubled at gas stations. But once again, it isn't enough to make up the differences you found.

Being almost out of gas and not knowing there's a cheaper station nearby or somebody else (like one's boss) paying for the gas, can't account for the majority of people overpaying, so stupdity must be the anwer.

It's been said that the two most common elements in the universe are hydrogen and stupidity. Unfortunately, there's no infrastructure to power our cars with either of them.