
There still exists a 20-30 cent difference between the unbranded versus the branded stations. What is not as noticable is with the inclusion of the Folsom branded stations, comparison of like-branded stations still shows Amador County 10-15 higher than the Valley.
I am still not convinced that branded stations have to purchase from their distributor but I cannot cite a reputable source to confirm.
Update: I believe the article I read that seems to imply that all gas comes from the same place and is the same gas until additives are introduced post-refinery was from the May 08, 2003 Sacramento News & Review.