Not only that but ethanol content in gasoline has to be standardized because auto makers have to know the percent of ethanol in passenger vehicle fuel to properly design their engines for efficiency and cleanliness. Imagine if you could fuel up at Citgo, but not at BP, or if there were different blends of fuel the consumer had to choose from depending on what types of fuel their vehicle's engine can use. It would be a mess, and really doesn't make any sense. Big oil is so big, that if government never steps in to promote renewable sources of fuel, the oil companies will never do it, and we will still be a petroleum based economy by the next century, with way too much carbon in the atmosphere.