In present study, the energetic and exergetic performances of a diesel engine fueled with conventional diesel and various biodiesel fuels were investigated experimentally. Energetic and exergetic performance parameters of the engine fueled with neat diesel, neat opium poppy and neat palm biodiesel fuels were calculated and compared with each other. Moreover, the sustainability analysis was carried out in the study. The findings of this study indicated that the energetic and exergetic performance parameters were profoundly affected by the engine speed and the fuel type. Both the thermal and exergetic efficiencies were the highest at the engine speed of 1600 rpm for all tested fuels. At this engine speed, the lowest thermal efficiency of the engine occurred with palm biodiesel as 34.92%, while the highest thermal efficiency value was 35.85% with diesel fuel. The exergy efficiencies of corresponding fuel types ranged from 32.50% to 33.64% for palm biodiesel and diesel fuels, respectively. In addition, the difference between the exergy efficiencies of diesel fuel and opium poppy biodiesel fuel was about 0.90%. Both the energy and exergy efficiencies diminished with the increment of engine speed higher than 1600 rpm for all fuel types. The maximum values of sustainability index for all fuel types were obtained at the engine speed of 1600 rpm. The best exergetically- sustainable fuel was the diesel fuel followed by the opium poppy biodiesel fuel. According to the results, opium poppy biodiesel might replace with the conventional diesel fuel due to the similarity of energetic and exergetic performance parameters.