Studies on the effective use of available fuel resources and the emission reduction of vehicles towards clean energy are always of interest for the sustainable development goals of the world nations. For that purpose, this paper studies the effects of nitro-paraffin-based fuel additives on the performance and emission characteristics of spark-ignition engines of motorcycles running on E5 gasoline-ethanol blends. The additive substance is referred as Maz-Nitro (Maz) supplied by Maz Energy Pte Ltd., which employs a unique combination of nitro-paraffins and 1.82% of ester oil. The studies were conducted on motorcycle engines by laboratory tests on the chassis-dyno and by field tests on the road under different engine operating conditions and different additive dosages blended in fuel. The results showed that the additive with the dosage of 750 ppm gives a good improvement of engine operation in terms of fuel-saving and emission reduction. The average power improvement and fuel-saving at engine full load are 2.82% and 2.97%, respectively. The average reductions of CO, HC, and NOx emissions are 9.05%, 12.8%, and 2.03%, respectively. The use of this fuel additive may significantly contribute to reducing environmental pollution and saving fuel resources.