What are the differences between China 6b and China 6a?
2 Answers
The differences between China 6a and China 6b are mainly divided into five aspects, as detailed below: 1. Carbon monoxide emissions: (1) The China 6a emission standard stipulates that carbon monoxide emissions must not exceed 700 milligrams per kilometer. (2) The China 6b emission standard stipulates that carbon monoxide emissions must not exceed 500 milligrams per kilometer. 2. Non-methane hydrocarbon content: (1) China 6a non-methane hydrocarbons must not exceed 68 milligrams per kilometer. (2) China 6b non-methane hydrocarbons must not exceed 35 milligrams per kilometer. 3. Nitrogen oxide content: (1) China 6a nitrogen oxides must not exceed 60 milligrams per kilometer. (2) China 6b nitrogen oxides must not exceed 35 milligrams per kilometer. 4. PM fine particles: (1) China 6a PM fine particles must not exceed 4.5 milligrams per kilometer. (2) China 6b PM fine particles must not exceed 3 milligrams per kilometer. 5. PN fine particles.
I remember when I bought a China 5 car a few years ago, the emission standards gave me a headache. Later, I learned that China 6 is divided into a and b, with the biggest difference being in strictness. China 6a is more of a transitional version—it has looser limits on pollutants like nitrogen oxides and carbon monoxide, meaning emissions might be slightly higher when driving in the city. China 6b, implemented after 2020, is much stricter, significantly lowering the limits for all pollutants, especially particulate matter and nitrogen oxides. It also introduced Real Driving Emissions (RDE) testing to ensure vehicles meet standards under normal driving conditions, unlike lab tests that are easier to cheat. Additionally, the OBD system was upgraded to monitor faults in real-time, affecting both my sense of driving safety and maintenance costs. Overall, the b version is more eco-friendly and efficient, so I recommend prioritizing it when buying a new car.
