The present study focuses on the application of neem biodiesel and dimethyl carbonate as alternative fuels for modern engines, examining their properties and emission characteristics under varying load conditions. Experimental results show improved emission characteristics at an optimum load of 80%. There was a decrease in both hydrocarbons and carbon monoxide and an increase in additive blends with biodiesel. Similarly, smoke opacity was higher for pure biodiesel but fell with an increase in the percentage of additives. Therefore, the present article highlights the utilization of biodiesel in modern vehicles using various fuel additives under different operating conditions.