I was told (no, I do not have a reference, appreciate it if anyone has one either way) that the 10% ethanol sticker means UP TO 10%, that the gas company can lower the amount based on availability. With the way corn prices jumped, I would not be surprised if it was less.
Ethanol[edit] United States
In the United States, ethanol is sometimes added to gasoline but sold without an indication that it is a component.
In several states, ethanol is added by law to a minimum level which is currently 5.9%. Most fuel pumps display a sticker stating that the fuel may contain up to 10% ethanol, an intentional disparity which allows the minimum level to be raised over time without requiring modification of the literature/labelling. The bill[citation needed] which was being debated at the time the disclosure of the presence of ethanol in the fuel was mandated has recently passed.
Last month, the maximum was raised to 15%.