What does the National IV logo refer to?

[LaJoseph]

IV is a Roman numeral, corresponding to the Arabic numeral 4, so National IV is the National 4 standard. Here are the methods to check which national standard a car belongs to: 1. Check the back of the car's environmental protection label. 2. Estimate the car's emission standard based on its production year. 3. Take the vehicle registration certificate to the local DMV for inquiry. 4. Check the emission standard description on the vehicle qualification certificate. The national standard refers to the National Motor Vehicle Pollutant Emission Standards, which regulate the content of harmful gases such as carbon monoxide, hydrocarbons, nitrogen oxides, particulates, and carbon smoke emitted from vehicle exhaust.