Managing plastic waste while ensuring sustainable energy solutions is one of the critical challenges in modern engineering. The present study aims to address the combined issues of plastic waste management and engine exhaust gas emissions by replacing 50% of diesel with 50% of oil produced from plastic waste. Experimental tests were conducted on a common rail direct injection engine using Diesel Plastic Fuel (DPF = 50% Diesel + 50% Waste Plastic Fuel) and DPF blends containing 5%, 10%, and 15% Furfuryl Alcohol (FA), such as DPF-FA5, DPF-FA10, and DPF-FA15 across engine loads ranging from 20% to 100%. Key parameters such as Brake Thermal Efficiency (BTE), Brake Specific Fuel Consumption (BSFC), cylinder pressure, heat release rate, and emissions (CO, CO, HC, NO, and smoke opacity) were analyzed. The results were normalized and integrated into a Python-based program to estimate the performance index, adapting a novel optimization method using Kissing Numbers that allows the identification of optimal fuel configurations. The addition of FA improved engine combustion which resulted in an 8.2% increase in BTE, a 9.8% reduction in BSFC, and a 23.4% decrease in smoke opacity compared to DPF. While NO emissions increased by 19.5%, CO and HC emissions were reduced by 2.9% and 13.1%, respectively. DPF-FA15 was identified as the optimal blend for high loads that demonstrate the potential of FA to balance performance and emission characteristics using Kissing Numbers. The results highlight the potential of FA as a sustainable additive for diesel-plastic blends that offer a viable solution to reduce plastic waste and enhance engine performance and environmental sustainability.