Plasma activation is an innovative concept for converting liquid or gaseous fuels into reactive species. However, there are few studies that focus on activating air to enhance combustion efficiency and reduce emissions of toxic pollutants such as PAHs. In this study, a plasma-enhanced combustion system was used to increase the amount of free radicals in intake air and enhance the combustion efficiency. The experimental results show that the reduction in pollutant emissions was enhanced with the increase in voltage, and that this also reduced the amount of fuel used. The optimum voltage of the plasma-enhanced system was 3200 V, and this reduced total PAHs by 20.7%, total BaPeq by 20.5%, CH4 by 50.0%, NMHC by 57.7%, THC by 57.1%, CO by 60.2%, NOx by 70.7%, CO2 by 19.8%, and PM by 42.8%, and achieved fuel savings of 12.1%.