As long as we're quoting Wiki, we might as well ask why ethanol was first used in gasoline and when.

"Gasoline containing up to 10% ethanol began a decades-long growth in the United States in the late 1970s. The demand for ethanol produced from field corn was spurred by the discovery that methyl tertiary butyl ether (MTBE) was contaminating groundwater.[27][30] MTBE's use as an oxygenate additive was widespread due to mandates in the Clean Air Act amendments of 1992 to reduce carbon monoxide emissions. MTBE in gasoline had been banned in almost 20 states by 2006. Suppliers were concerned about potential litigation and a 2005 court decision denying legal protection for MTBE.[citation needed] MTBE's fall from grace opened a new market for ethanol, its primary substitute.[27] Corn prices at the time were around US$2 a bushel.[citation needed] Farmers saw a new market and increased production. This demand shift took place at a time when oil prices were rising."

Every normal man must be tempted, at times, to spit on his hands, hoist the black flag, and begin slitting throats. H. L. Mencken