A novel protocol has been explored for fast and energy-efficient biodiesel production from waste mustard oil (WMO) using infrared radiated reactor in presence of heterogeneous Amberlyst 15 catalyst. High biodiesel yield (FAME content 97.13%) was obtained from WMO via simultaneous esterification-transester ification reactions in only 0.5 h using an energy-efficient, far infrared radiation (FIR) at the derived optimal conditions predicted through Taguchi Orthogonal Design (8:1 methanol to WMO molar ratio, 6 wt.% catalyst concentration, 800 rpm impeller speed). Experimental observations at the derived optimal conditions indicated much lower FAME yield (43.82%) with conventionally heated reactor even at the expense of 4 times energy input as that of FIR promoted protocol. Promising engine performance was observed at various blends of FIR produced optimal biodiesel with commercial petro-diesel. Notably, in comparison with petro-diesel, lower exhaust temperature was observed for all blends, indicating better engine durability and lower engine depreciation. The exhaust emissions measurements indicated that CO (0.05%) and hydrocarbon (HC) emissions (<0.00002) for B-100 were well below standard Euro-VI emission norms and were observed to decrease gradually with increase in biodiesel percentage in the blended fuel. (C) 2016 Elsevier Ltd. All rights reserved.