4G9 series engines are mature products being mass-produced by Mitsubishi Motors of Japan, which have reached the world advanced level in terms of structure, performance and reliability. The main advantages of the product: compact structural design, smaller overall size and lighter weight compared with the same displacement engine. The main parts of the engine have high rigidity, and the main moving parts are lightweight, which reduces the friction loss of the moving parts. High-efficiency combustion methods such as rolling combustion and optimal fuel injection are adopted. By strengthening the rigidity of the cylinder block and crankshaft and using damping resin materials on some parts, the noise of the engine is minimized. Adopting advanced electronic fuel injection system, the emission can reach Euro 3 and Euro 4 standards, and the fuel consumption rate is low.