Supply, general consumption, seasonal usage, diesel vs gas production changeover, spot shortages, "boutique blends" (custom requirements per state) point of sale "cash replacement cost" lag, prices in foreign (export) markets, and reaction to environmental legislation....etc etc etc
Of course all of the above work to create confidence, fear, caution and other logical and emotional reactions in the minds of speculators, who are bidding on unleaded gasoline futures and other derivatives in the US commodities markets...every minute of every day...from around the world.
This is all pretty much unseen and unreported, but you could follow it if......if you can stand to follow it.
If you like gambling, it's the ultimate online casino game.
It is indecipherable, which is why it is kind of like...gambling, if you are speculating!
It is why the “Invisible Hand” that liberals despise (unless they are making money off it) does a far better job of handling prices and such, because you have millions of people voting with their money and desires to figure out how much of any kind of blend or amount should go anywhere.
When you put that into the hands of a small group of people (like some Politburo planning committee) they cannot possibly know all the things that cause millions to vote with their own money...and that small group always gets it wrong!