On the other hand, I mostly use the cheaper stuff from the supermarket. Saves .10 to .25 per gallon and I've used in my 2003 very often since buying it new. No maintenance problems in seven years.
It does all come from the same place, though. In our market, every drop of gasoline comes from Western Refining in Gallup, NM. The additives are added by the tanker when it fills the storage tanks at the final vendor. Larger markets often receive gas from different refineries, but the difference is still pretty much in the additives.