This study conducted engine tests on utilizing reduced graphene oxide (rGO) and graphite (GT) nanoparticles (NPs) in varying proportions in a diesel engine. The experiments were performed with a four-stroke diesel engine featuring a water-cooled, three-cylinder configuration. Exergy and sus-tainability analyses are performed using the experimental work's findings. The results of test fuels containing GT and rGO NPs additives were compared with standard diesel fuel. Additionally, rGO and GT NPs are used in diesel fuel at concentrations of 50 ppm and 75 ppm, designated as Die-sel+50ppm GT, Diesel+75ppm GT, Diesel+50ppm rGO, and Diesel+75ppm rGO. The engine tests are made at a constant 1800 rpm and variable torques. The results indicate NPs-added fuels offer better exergy and sustainability performance than diesel. The Diesel+75ppm rGO blend resulted in the sustainability index and highest exergy efficiency with average improvements of 6.2%, and 12.1% respectively, over conventional diesel. Moreover, the highest average reduction in exergy destruction is achieved with Diesel+75ppm rGO at 21.6%, while the lowest average reduction is observed with Diesel+50ppm GT at 15.2%, compared to diesel. With greater amounts of rGO and GT NPs in diesel fuel, the surface-to-volume ratio grows, enabling a broader combustion zone and improved thermal exchange. It was determined that the utilization of nanoparticle additives in diesel fuel, along with an increased concentration, enhances both its exergy efficiency and sustainability.