Today, gasoline and diesel fuel with high sulfur content are widely used in Mongolia. According to the analysis results of fuel sample, the sulfur content in gasoline and diesel meet the Mongolian National Standard requirements, but the sulfur content in gasoline is two to eight times higher than that of the Euro 4 standard, and the sulfur content of diesel is also 22 to 23 times higher than that of the Euro 4 standard. We tested Lubricon A-112M, which is an enzyme-based additive used in bunker fuel. In this study, we conducted an emission factor measurement by using two vehicles with gasoline and diesel engines under three conditions; using ordinary fuel, using fuel additive once, and using fuel additive for six months. Then, vehicle emission was predicted by comparing EF measurement results. The results show that for the vehicle with a gasoline engine, when using Lubricon A-112M, the emission level of NOx decreased by 1.69 to 1.87 times (26%-37%). For the vehicle with a diesel engine, when using Lubricon A-112M, the emission level of NOx decreased by 1.04 to 1.51 times (4%-30%), and the emission level of particulate matter (PM) decreased by 1.52 to 2.06 times (20%-26%). We compared the results obtained in real situation with those obtained in the scenario in which the fuel additive was added and the new gas exhaust standard was applied. In this scenario, the fuel additive was used in 30% of all vehicles from 2016, and the Euro 4 standard was applied to all vehicles except those over 10 years old from 2020. The results of the scenario show that the emission level of NOx and PM reduced by approximately 8% and 13% in real situation until 2020. After that, NOx and PM reduced by 6-22% and 16-30%, respectively.