Before high prices 3 years ago I was using any gas station. When prices climbed I compared prices and found supermarkets gas stations cheaper and used them until I began to eco-drive, eco-mod and hypermiling...
I read an article about differences between some gas (much less dust) and additives (cleaners) and decided to try some gas with additives. At the middle of the 1st tank I found my car accepting lower rpm in 5th from 1500 to 1300, then to 1100 after a couple tanks.
As this gas with additives isn't more expensive than buying some additives I decided to continue with this gas. I also found that the gas station I used is the cheapest gas with additives near my commute. Last this gas is extracted, refined and distributed by a French company for which I worked while I was student.
When I have to fill up far from home, I fill up with the same gas I use whatever is the price as it's rare. Rare times I fill up with another gas are when there is strikes and I can't find my gas...
My first goal in saving gas is to save energy and to lower pollution. The money saving helps me into my goal by buying a little bit more expensive gas (+5% while I'm saving 45%) and invest in energy saving projects : better oil, battery, tires... for the car, some insulation for doors and water heater at home; and my preferred a solar panel and a charge controller for a geek project and have fun
Denis.