A similar big price differential happened in Iowa at Murphy in Mason City this past summer. 91 was 11 cents higher than 89 (still available at that time) and 93 was like another 60 cents higher. I was using 91!!!!!!!!!!!!!! Before I headed south, the difference at Murphy was 12 cents between 87 & 91, and 93 was another 10 cents higher. However, I did see 87 E-10 vs 87 non-ethanol being priced as much as 40 cent difference in another IA town an brand, with E-10 92 octane almost the same price as the non-ethanol 87.