The rapid growth in industrialization and the automotive sector has led to overuse of conventional energy sources and significant pollution. Biodiesel, produced via transesterification from non-edible oils like Deccan hemp, Karanja, Rapeseed/Canola, Yellow mustard, and Cottonseed oil, emerges as a promising renewable fuel. Enhanced with 5% bioethanol for better combustion, ten QUAD BLEND fuels were tested in a single-cylinder diesel engine at various compression ratios. The SD75B10C10EA5 blend showed superior brake thermal efficiency (up to 24.80%) and reduced emissions compared to diesel, with significant reductions in CO, HC, and NOx emissions. The SD75C10D10EA5 blend notably minimized emissions, with CO reductions up to 60% and HC reductions up to 71%, while maintaining efficiency close to diesel. These results indicate that biodiesel blends, especially with cottonseed, rapeseed, and Deccan hemp oils, offer effective and environmentally friendly alternatives to conventional diesel.