What are the differences between China 6b and China 6a?

[DiAniyah]

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.

[Arya]

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.

[VanVanessa]

As an ordinary person who often pays attention to urban air quality, I have studied the differences between China 6a and 6b standards. The 6b standard is clearly superior, with lower pollution limits—carbon monoxide is reduced by about 30%, and nitrogen oxides are also more strictly regulated. The key is that it incorporates RBD (Real Driving Emissions) testing, which simulates emissions in urban congestion scenarios, unlike 6a, which relies solely on fixed lab tests. This directly impacts daily air quality, and I’ve personally noticed a significant improvement in air quality in my big city since the widespread adoption of 6b-compliant vehicles. Additionally, the OBD (On-Board Diagnostics) monitoring is more refined, with faster warning light alerts for faults. Although vehicles meeting the 6b standard might be slightly more expensive initially, the long-term environmental benefits are worth it.

[SanJaxson]

China 6a and 6b are both automotive emission standards, but 6b is stricter. As a transitional phase, 6a was implemented in 2019 with higher emission limits; 6b officially took effect in 2020, reducing pollutants like CO and NOx by over 50%. 6b also requires RDE (Real Driving Emissions) testing, which monitors emissions during actual road driving for excess levels—more reliable than 6a's lab tests. Additionally, the OBD system's fault diagnosis capabilities were enhanced. These measures make 6b-compliant vehicles cleaner and safer in real-world conditions.