I believe you are mistaken that ethanol can even be made from petroleum. Please provide a link that discusses it.
I take it you never studied organic chemistry. Crack the hydrocarbons in petroleum using a zeolite catalyst, for example, then separate and partially oxidize the C2 portions to produce ethanol. It would take to long to post my chemistry texts on line, but most of the organic chemicals we use come from petroleum. I’m taking almost all plastics, pharmaceuticals, etc.
Ethanol would be a waste, even if it could be produced from petroleum (lower gas mileage, can’t transport by pipeline, can’t ignite by itself at low temperatures, and so on).