To facilitate the activities of Indonesians, government issues many public transportations, furthermore a lot of Indonesians uses their own private vehicle as well. Unfortunately, all of these transportations still utilize fossil fuel as energy sources. And with the increasing number of populations, the number of transportations also rises. This condition shows that Indonesia is still dependent on non-renewable energy sources. One alternative energy currently being developed as an alternative fuel in motorized vehicles is bioethanol. The addition of bioethanol to gasoline will certainly change the fuel properties, the fuel will be more difficult to self-ignite so the pressure generated in the combustion chamber will be more consistent. Coefficient of variation (COV) represent the ratio of the standard deviation to the mean of a set of data, in this study in cylinder pressure data (IMEP) is used. Based on previous research that discussed the analysis of emission gas and fuel consumption on SI engine fueled with low-grade bioethanol and oxygenated additive, the authors examined further to analyze the characteristic of ethanol blend and oxygenated additive to COVIMEP and Specific Fuel Consumption (SFC) of various fuel mixture as well as COVIMEP correlation with SFC at variable engine speed were investigated. The result of study shows that ethanol blend and oxygenated additives in gasoline decrease variation in combustion pressure occurrences, lower COV. Ethanol-gasoline blend increased SFC compared with pure gasoline, while ethanol-gasoline blend with additive slightly reduce SFC compared with their own respective mixture.