I'd like to know this right now.. is brand name gas better for my new Yaris?

[fantabulousbaby]

So many myths out there.. need some advice.. of course I wanna save money and get the cheapest gas around me.. and there are plenty of non-brand gas stations near me.. for majority of the time I'd rather use the convenient Sam's Club gas across the street from me.. but I've also spoken to firm believers that you get better gas mileage or even prevent the 'check engine' light problems down the road.. please explain! I'm willing to go to Chevron and pay more if it's true! I spoke to someone who used to 'study' oil/gas and said that the non brand name stations essentially buy the gas that is 'rejected' by brand names like Shell and Chevron.. I need to fill up tomo. morning and hopefully will have insight by then! (Fyi in my area, the diff. b/t name and brand name can be 40 cents plus per gallon). Thx