I found this article on Wikipedia interesting on differences in gas brands. It may not be a difference in the octane or energy rating directly, but the cleaner injectors being able to atomize it better.
Top Tier Detergent Gasoline - Wikipedia, the free encyclopedia
"While General Motors' fuels engineer Andrew Buczynsky says that no one has identified the exact molecule in gasoline that causes engine buildup, he says that top tier detergent gasoline will remove the deposits.[15] Engine "gunk" typically builds up in fuel injectors, intake valves, and in time may foul combustion cylinders. Without some level of detergents, engine deposits form in most vehicles and this causes reduced fuel efficiency, acceleration, and power, as well as increasing emissions, rough idling, and increased motor repairs.[16]"