 Mitsubishi lowered the friction of the engine by including elastic grinding of the valve stems, adopting a high-efficiency shroud equipped plastic impeller in the water pump and using 0W-20 low-viscosity oil.Mitsubishi increased the combustion efficiency by optimizing the design of the cylinder head intake and exhaust ports, by incorporating the MIVEC system on both intake and exhaust valves and by using injectors that give an ultra micro droplet fuel spray.To lower the engine's weight, Mitsubishi used die-cast aluminium for the cylinder block, plastic for the cylinder head cover and intake manifold, and stainless steel for the exhaust manifold.