Here in Mass gas in no name stations are running around $2.05 per gallon, a lot less @ BJ's, while in big name stations are 15 to 20 cents higher. Feels good at low cost gas when filling a 80 gallon ...
They add it later but it is a secret like the recipe for coke or Bush beans. They may even add it several weeks later. Seriously I think the bigger stations that have fuel that sits for the shortest time is best. I did fillup at a small country station once with my car and was missing in a half hour. The car engine that is. Water in fuel is the biggest issue and that is easily remedied. I agree that cheap gas is just less expensive.