I used to go to Shell gas station. One reason is when I started to driving in 1998, I heard from fellow graduate students that “Shell gas is the best”. Another reason is there is a Shell gas station near my home.
But after I tried the BP (British Petrolum, formerly Amoco) station lately, I changed my mind. It seems to me BP invigorate gas lasted longer than the Shell gas, at least to my 2001 Nissan Altima. I guess it could be one time thing, as BP invigorate contains some additives to clean up the engine, which the Shell could not do for some reason.
Bottom line is, I am going to try it for a while, and see if this effect lasts.