Do you pay extra for "branded" gas from companies like Exxon, Mobil, or BP? IMHO – Gas from any reputable company is gas.
The other day, I paid $3.61 per gallon at my local BJ's Club. On the way home, I saw prices as high as $3.84. In my area, the Citgo consistently has the lowest prices and the Shell has the highest. At some point, one would expect the Shell customers to switch to Citgo; however, they do not.
Why not? Despite all the protestations about gas prices, I think most people are lazy and not sensitive to gas prices. They just fill up in the most convenient spot without even considering the cheaper gas one block away.
Your theories?