Adding nanoparticles to base fuel is one of the ways to improve engine performance. Metal nanoparticles and metal oxides have positive effects on engine performance, but their use is limited due to their toxicity. Therefore, it is necessary to use environmentally compatible nanoparticles. In this research, functionalized spherical carbon nanoparticles have been synthesized, analyzed and used as fuel additives. These nanoparticles have low toxicity and environmental impact. They are easy to synthesize and have low production cost. The functional groups used in these particles help stability in fuel and oxidation. They were added to gasoline with two concentrations of 40 ppm and 60 ppm, and the blends were used in the Tiba Euro 4 spark-ignition engine. A series of experiments were conducted to study the effect of nanoparticles on engine performance and pollutant formation. The performance parameters and pollutant concentrations were measured at different speeds in full load mode. The results showed an improvement in the combustion process which led to increase of the engine’s torque and power and decrease of exhaust gas temperature and fuel consumption, and in some cases, pollutant formation. The best result was obtained at 3500 rpm and with a nanoparticle concentration of 40 ppm, for which the engine torque and power were increased by 4.6% and 3.4% respectively, and brake specific fuel consumption and carbon monoxide and unburned hydrocarbon concentrations were decreased by 8.6%, 40% and 30.6% respectively, compared to the pure gasoline results.