What do China 5 and China 6 vehicles mean?

[VonBryce]

China 5 and China 6 vehicles refer to automotive exhaust emission standards, which regulate the content of harmful gases such as carbon monoxide, PM, and soot emitted from vehicle exhaust. The higher the number, the later the standard was issued, and the stricter the energy-saving and emission-reduction requirements for vehicles. The transition from China 5 to China 6 includes improvements in intake and exhaust efficiency, exhaust gas recirculation efficiency, etc., with the aim of reducing the levels of harmful gases. The China 6 emission standard is an upgraded version of the current China 5 standard, imposing more stringent limits on the emission of carbon monoxide, total hydrocarbons, non-methane hydrocarbons, nitrogen oxides, and particulate matter mass compared to the China 5 standard. Additionally, it introduces new regulations on the number of particulate matter emissions.