Vehicular emissions limits have been reduced throughout the world in compliance with environmental legislations.With the rapid increase in the number of flex-fuel vehicles on the market, the consumption of ethanol has also increased. As a result, there is expected to be a large abundance of unburned alcohol from tailpipe gas emissions. Another important factor arising from the use of ethanol is the formation of tropospheric ozone.The objective of this study was to measure the amount of unburned alcohol and legislated emissions as well as the ozone formation potential of a passenger (light-duty) vehicle fueled with gasoline containing different concentrations of ethanol.The main conclusion is that unburned alcohol emissions increase in direct proportion to the ethanol content in the fuel. The unburned alcohol was measured by two techniques: gas chromatography and FTIR. Regarding ozone, it was concluded that ozone formation increases in direct proportion to the exposure of the exhaust gases to solar radiation and the ethanol content in the fuel.