ethanol is added as an oxygenate,to reduce nitrogen compounds. it replaced the toxic MBTE addititve. then it was touted as an "extender" to stretch gasoline supplies,at a small extra cost,not forseeing it's negative effect on food supplies.
there's nothing wrong with CO2 emissions.
I doubt the world's automobiles contribute to global climate effects. a single volcano has FAR more of an effect,and the SUN is the greatest factor. Neither of those can be controlled or compensated for by humans.