On July 24, 2009, ABC’s 20/20 aired a special program titled “Over a Barrel: The Truth About Oil“. You may download and watch the segment of the program dealing with gasoline stations and margins here or here.
In the context of retail gasoline margins, some notable quotes from the program:
“The average retailer makes 10 cents or less on a gallon of gasoline. There’s a better profit margin in convenience stores.” Sal, station owner
“That corner gasoline station has never been able to make a profit on gasoline.” Sal, station owner
“Intense competition among local gas stations is what keeps profit margins on gasoline low. After all, people will drive miles just to save a couple of pennies a gallon.” Charles Gibson, ABC News
“It is time for smart, entrepreneurial, and customer-friendly retailers to utilize the tools available to them (see Posts 2 & 3 below) to improve their profit margins on gasoline and diesel fuel while saving people more than a couple of pennies a gallon“ Tom Langan, WTL Trading
Fuel Price Protection Programs 
I quite like reading through a post that will make people think.
Also, many thanks for permitting me to comment!