Several gasoline-ethanol-water multicomponent systems at temperatures of 283.15, 293.15, and 313.15 K were studied, to obtain water tolerances and ethanol concentrations at equilibrium in the upper gasoline-rich phase. The lower aqueous phase was not studied, because of its very small volume. The ethanol and water concentrations were determined by a chromatographic method, using the external standard method for quantification, whereas no other gasoline component was determined. Moreover, the influence of the gasoline volume in the tank was simulated and studied in the laboratory. From experimental results, we conclude that the ethanol concentration decreases as the tank becomes more empty, whereas it is only slightly affected by the temperature within the studied temperature range. A similar behavior was observed for the water tolerance, when the water volume inside the tank corresponds to 0.5 vol % of water. In addition, the loss of ethanol that is drawn into the aqueous phase diminishes dramatically when the water volume in the tank diminishes, and the loss of ethanol becomes negligible when this volume corresponds to less than or equal to0.05 vol % of water.