This paper describes some of the advanced technologies designed for low fuel consumption in the new P11C in-line 6-cylinder, heavy duty diesel engine which has two power ratings of 239kW at 2100rpm and 221kW at 2150rpm.The new engine's displacement has been increased from 8.8 liters of the base engines (EP100, P09C) to 10.5 liters without an increase in either engine weight or overall dimensions. The turbocharger has a mixed-flow turbine which improves the fuel consumption by improving the turbine efficiency. The piston, made from ductile cast iron, improves the fuel consumption and reduces the exhaust emissions by heat insulation of the combustion chamber (i.e. the ductile cast iron has a lower thermal conductivity than the previous piston's aluminum alloy). Additionally, this engine achieves lower friction loss by an intake air system with low air flow resistance and by roller cam followers.Due to these advancements the P11C achieves a BSFC of 184g/kWh at 1500rpm, and meets the 1989 Japanese exhaust emission regulations.