What are the differences between National IV, National V, and National VI?

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The differences between National IV, National V, and National VI lie in the principles of fuel adoption and emission standards. Below are the detailed explanations: Principles of fuel adoption are different: During the National IV and National V phases, the emission standards for diesel and gasoline vehicles were different; National VI adopts a fuel-neutral principle, meaning the emission limits are the same regardless of the fuel type used. Emission standards are different: Compared to National III, National IV standards reduced nitrogen oxide emissions by 30% for light-duty vehicles and 50% for heavy-duty vehicles; National V standards, based on National IV, further reduced nitrogen oxide emissions by 25% for light-duty vehicles and 43% for heavy-duty vehicles; National VI standards, building on National V, reduced particulate matter emissions by 40%, and for heavy-duty diesel vehicles, nitrogen oxides and particulate matter emissions were reduced by 60% compared to the National V phase.