The effects of alcohol composition on gasohol vehicle regulated emissions and fuel consumption were investigated in PETROBRAS tests. Four formulations of gasohols were prepared with the same base gasoline and 22% by volume of alcohol. Two formulations with ethanol from carbon hydrates fermentation; one using corn and the other sugar cane feedstocks. The other two using synthetic alcohol one from coal and the other from natural gas as feedstocks to the synthetic plants. Four Brazilian gasohol vehicles were tested over a Brazilian emission cycle.Changing alcohol composition will alter gasohol CO emissions compared with ethanol from sugar cane used as reference gasohol. The effects of ethanol composition on CO emissions have different responses for a particular vehicle model. HC, NOx, Aldehydes, CO2 and fuel consumption did not vary significantly. Additional investigations were designed to study corrosion effects and the results suggest that the alcohol from natural gas and from coal are potentialy more corrosive. Finally the paper discusses the role of alcohol addition to gasoline.