What do National V and National VI emissions mean?

[TimothyRose]

National IV, National V, and National VI refer to which stage of national emission regulations (National IV, National V, National VI) a vehicle's current exhaust status complies with. In simple terms, it indicates whether the vehicle's exhaust meets the National IV, National V, or National VI standard, with National VI being the most stringent emission standard currently. Introduction to emissions: A car is a mobile source of pollution, emitting major pollutants such as carbon monoxide (CO), hydrocarbons (HC), nitrogen oxides (NOx), and particulate matter (PM, PN), all of which are environmentally harmful substances that need to be controlled. Introduction to emission sources: The sources of vehicle pollutant emissions come from the exhaust pipe, crankshaft case, and fuel system.