What are the differences between National 5 and National 6 environmental standards?

[LaAllison]

The differences between National 5 (China 5) and National 6 (China 6) emission standards are as follows: Different emission standards: The National 6 emission standards are more than 30% stricter than National 5. Excluding the influence of driving conditions and testing, gasoline vehicles under National 6 reduce carbon monoxide emissions by 50%, total hydrocarbons and non-methane hydrocarbons by 50%, and nitrogen oxide emissions by 42%. Different implementation times: The National 5 standard was implemented nationwide on January 1, 2017. National 6 has been in effect since July 1, 2019. Different principles: Under National 5, diesel and gasoline vehicles had different emission standards, but National 6 adopts a fuel-neutral principle, meaning the emission limits are the same regardless of the fuel type. Different issuing authorities: National 5 was issued by the Ministry of Environmental Protection, while National 6 was jointly issued by the Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection, and Quarantine. Different letter representations: National 5 is denoted by "V," while National 6 is denoted by "VI." Different monitoring requirements for plug-in hybrid electric vehicles (PHEVs): Compared to National 5, National 6 has enhanced monitoring requirements for PHEVs, including energy storage systems, thermal management systems, regenerative braking, drive motors, generators, and other regulatory aspects. Different prices: National 6 vehicles are equipped with additional components compared to National 5. Moreover, automakers incur extra costs for vehicle certification, testing, and production, resulting in significantly higher prices for National 6 vehicles than National 5 vehicles. Different scrapping timelines: Although the government has abolished mandatory scrapping timelines, older vehicles may be banned from roads, effectively rendering them scrapped. For example, a National 5 vehicle purchased in January 2019 and a National 6 vehicle purchased at the same time may both have a 15-year registration period, but their actual usability will differ. For instance, as of now, National 3 vehicles from 2010 and National 4 vehicles from the same year can still operate in Beijing, but many older vehicles are effectively scrapped due to increasing city restrictions. Thus, even for vehicles of the same age, their usable lifespans differ. National 5 emission limits are as follows: Gasoline vehicles must not exceed 1,000 mg of carbon monoxide per kilometer driven. Non-methane hydrocarbons must not exceed 68 mg per kilometer, nitrogen oxides must not exceed 60 mg per kilometer, and PM (particulate matter) must not exceed 4.5 mg per kilometer. National 6 has two sub-standards: National 6a and National 6b, as follows: National 6a emission limits: Gasoline vehicles must not exceed 700 mg of carbon monoxide per kilometer driven. Non-methane hydrocarbons must not exceed 68 mg per kilometer, nitrogen oxides must not exceed 60 mg per kilometer, and PM must not exceed 4.5 mg per kilometer. National 6b emission limits: Gasoline vehicles must not exceed 500 mg of carbon monoxide per kilometer driven. Non-methane hydrocarbons must not exceed 35 mg per kilometer, nitrogen oxides must not exceed 35 mg per kilometer, and PM must not exceed 3 mg per kilometer. Due to the National 6 emission policy, although National 5 vehicles are not currently restricted in normal use (no driving bans or license plate restrictions), their resale value will be significantly affected. For truck owners, if they purchase a truck on loan for freight transport, the depreciation of the vehicle after paying off the loan directly impacts their net profit during that period. A higher residual value means greater earnings for the owner. From this perspective, National 6 vehicles, with longer usability and better road access, offer more advantages.

[Shaun]

I recently researched emission standards and found the differences between China 5 and China 6 quite significant. The China 5 standard, implemented since 2017, already imposed strict limits on pollutants like nitrogen oxides and particulate matter. But China 6 takes it further – especially the China 6b phase launched in 2019, which slashes emission limits even more drastically (e.g., nearly halving nitrogen oxide limits) and introduces Real Driving Emissions (RDE) testing to ensure cleaner performance on actual roads. This means new vehicles now feature advanced catalytic converters and more precise OBD diagnostic systems, with improved dashboard alerts. The trade-off? China 6-compliant cars may cost 2,000–3,000 RMB more and require stricter maintenance for batteries or engines. Long-term, though, they reduce smog and protect air quality. For us car owners, opting for China 6 models when upgrading ensures eco-friendliness and fuel efficiency, while avoiding the obsolescence risks of China 5 vehicles in the used-car market.

[KiaraDella]

From an environmental perspective, let's talk about the differences between China 5 and China 6 emission standards. While the China 5 standard limited CO and nitrogen oxides, I found the China 6 standard to be truly stringent—it lowered all core pollutant indicators. For example, the CO limit was reduced from 1000mg/km to 500mg, and it added monitoring for non-methane hydrocarbons (NMHC). The testing methods also became more realistic, such as measuring emissions not just in lab conditions but also during urban congested driving. This means automakers must adopt more technologies like GPF (Gasoline Particulate Filters) to meet the standards, making vehicle emissions cleaner. However, car prices may rise slightly, and maintenance costs could be higher. Still, I think it's worth it—it helps reduce PM2.5 and acid rain issues while also benefiting climate change. When buying a car, I insist on choosing China 6-compliant models to avoid outdated, excessive-emission vehicles.

[VonJessica]

The main differences between China 5 and China 6 standards lie in emission limits and testing. China 6 is stricter, with pollutants like nitrogen oxides limits reduced by approximately 50%, and includes RDE (Real Driving Emissions) testing to ensure emission reductions under real driving conditions. Technically, China 6 requires upgraded OBD systems capable of real-time fault monitoring. In practice, new China 6-compliant vehicles are slightly more expensive but more fuel-efficient and easier to maintain, while older China 5 vehicles face phase-out. Overall, environmental protection is significantly enhanced.

[Braxton]

The main differences lie in the emission standards and testing methods. China 5 only requires basic limits, while China 6 has lowered the limits for nitrogen oxides and carbon monoxide, such as reducing CO to below 0.3g/km, and introduced RDE road tests to prevent cheating. Technologically, GPF and advanced catalytic converters are added to ensure cleaner emissions. When buying a car, China 6 vehicles are more expensive but more fuel-efficient, making them more environmentally friendly and reliable in the long run. China 5 vehicles may depreciate faster, so caution is needed when buying used cars. Choosing China 6 vehicles is the right priority.

[DeKinsley]

From an owner's perspective, the China 5 standard controls emissions of pollutants like CO or NOx, while the China 6 standard raises the bar by halving these limits again and adding real-world driving tests to prevent false reporting. Technological upgrades, such as more sensitive OBD systems for instant alerts, are implemented. The impact is that China 6 vehicles cost a bit more, but save significantly on fuel and greatly reduce air pollution, contributing to the environment. I've already replaced my old China 5 vehicle with a China 6 one, driving with more peace of mind and lower carbon emissions.