Misfueling accidents significantly damage the engines of both gasoline and diesel vehicles, and should be avoided by rapid and accurate fuel discrimination. Gasoline fuel contains bioethanol. Thus, the detection of ethanol vapor produced by gasoline can be used to distinguish between gasoline and diesel. In the present study, Pt-doped SnO₂ hollow nanospheres, Mg-doped In₂O₃ hollow microspheres, and Pt-doped ZnO nanostructures have been used as gas sensors to discriminate between gasoline and diesel fuels. All three sensors are able to detect and discriminate between gases evaporating from gasoline and diesel. Among the sensors, the Mg-doped In₂O₃ hollow microspheres show a significant gas response (resistance ratio = 4.97) quickly (~3 s) after exposure to gasoline-evaporated gas at 225℃, but did not show any substantial response to diesel-evaporated gas. This demonstrates that gasoline and diesel fuels can be discriminated using small and cost-effective oxide semiconductor gas sensors.