I don't know the answer to your question, but wanted to warn you that if you do use e85, your gas mileage will drop substantially. You can confirm this by looking at the fueleconomy.gov website. From a dollar standpoint, it may not make sense to run it.
If, on the other hand, you feel strongly about using it...........I hope you get a lot if helpful responses to your request-----and enjoy your trip to WDW!