Ethanol has a long history as an automotive fuel and is currently used in various blends and formats as a fuel for spark ignition engines in many areas of the world. The addition of ethanol to petrol has been shown to reduce certain types of emissions, but increase others. This paper presents the results of a detailed experimental program carried out under standard laboratory conditions to determine the influence of different quantities of petrol-ethanol blends (E5, E10, E25, E50 and E85) on the emission of regulated and unregulated gaseous pollutants and particulate matter. The ethanol-petrol blends were laboratory tested in two European passenger cars on a chassis dynamometer over the New European Driving Cycle, using a constant volume sampler and analyzers for quantification of both regulated and unregulated emissions. The emissions results revealed non-linear or insignificant changes in response to the addition of ethanol to the base fuel regarding certain parameters; and linear responses regarding others. Changes in regulated emissions were generally limited for blends up to E25; E50 and E85 caused greater changes in some cases. Particulate matter emissions followed a non-linear trend in response to blend ethanol content, with the highest emissions observed for the E10 blend. Unregulated emissions showed changes associated with the use of ethanol as a fuel component, including increases in concentrations of ethanol itself in the exhaust gas. Volumetric fuel consumption increased unambiguously as ethanol content increased, with blend energy content being an excellent predictor of fuel consumption for blends as high as E50.