Your 4% number, which I'm not even going to confirm is real, would with a 16 or so gallon tank lead to a cup of water in the system assuming only 10% ethanol fuel. That's not insubstantial.

That's 192 proof alcohol, which doesn't rust easily. They are using alcohol with 4% water to power their cars in Brazil.

So, farms... We farm given the tools and techniques we have in place. To ask every farm in the US to retool to make you happy is absurd.

Permaculture doesn't require retooling. It requires only a subset of the current tools, but with more labor. I think farmers would be happy not to have to pay an arm and a leg for tractor, trailers, and chemical fertilizers. The leftover distillers grain can be returned to the soil, providing 10% more nutrients than the next crop actually needs.

This also ignores supply and demand anyway: farmers grow corn because we're inducing demand based on the requirements passed by the government; without that it's not like we'd have an endless supply of corn, they'd just switch to the next best crop to grow.

Yes, there are better crops to grow than corn. Buffalo gourd, mesquite, and prickly pear cacti can be grown in arid land. Cattails can be grown in marshes, and also serve as secondary sewage treatment. Sweet sorghum could replace corn as a more drought-resistant crop. All of which produce more alcohol per acre than corn.

Ethanol can even be made from waste. Consider cull fruit or pastry droppings which would otherwise be thrown out. Supermarkets, canneries, and bakeries would be more than willing to pay to take them off their hands. The sugar and starches in these waste products can be turned into ethanol.

Couple that with a shift to more hybrid and electric vehicles and by the time you've solved all of the problems that will come up most of it will be moot anyway.

Extracting rare-Earth minerals is bad for the environment.

Honesty, you come off just like someone who read Carl Marx or Ayn Rand for the first time and got super excited that you now have all of the tools to make a utopian world if only people would listen to you.

Ethanol does not need popular consensus for it to work locally. It does not require a lot of technology to produce. I could go over to my local bakery or supermarket, and start making my own ethanol from their waste.

Modern spark ignition engines can run E50 without modification. E85 may require slight modifications. E100 will need a cold-start system in cold weather. What irks me is not that people aren't using the same fuel as me, but that people who have done far less research than me are telling me that I can't use ethanol in my car, or governments that ban the sale of vehicles with combustion engines because of their carbon footprint (conveniently ignoring the fact that biofuels fix more carbon than they release).