The local TV station did a story on this a few months ago. They went to an Exxon on a busy intersection and asked people why they were buying gasoline there when it is 8 cents a gallon across the intersection at a Stop-and-Go store. Most people shrugged and said they never noticed it. Their conclusion was that most people would just pull in where it was easiest rather than cross several lanes of traffic to get to the other side. Most didn't seem to care what the price was.
Oops, I meant "8 cents a gallon cheaper" across the intersection.