| The use of biofuels in the world is increasing due to their economic prices and an energy crisis. Bioethanol is an alternative renewable fuel suitable for use in internal combustion engines. When compared to the octane number of gasoline, this fuel has a relatively high octane number. Another major property is that bioethanol can reduce motor vehicle emissions when compared to fossil fuels. This study aimed to determine the number of exhaust emissions with fuel that uses a mixture of pertalite RON 90 gasoline and bioethanol. The test method uses a loaded engine with three rpm variations, namely 1200, 6000, and 9000 rpm, with exhaust emission measurement parameters consisting of CO2, CO, HC, and NOx. The test used four kinds of bioethanol mixtures, namely bioethanol 5% (E5), bioethanol 10% (E10), bioethanol 15% (E15), and bioethanol 20% (E20), in addition to pure gasoline RON 90 (pertalite). Measurement of exhaust emissions is carried out using an exhaust gas analyzer. The test results show that using a mixture of bioethanol as fuel does not reduce the total amount of exhaust emissions. The proportion of CO2 tends to grow as the bioethanol mixture increases, and vice versa for the percentage of CO. Meanwhile, the proportion of HC reduced as the bioethanol mixture rose, whereas the percentage of NOx increased. |