What are the differences between National V and National VI engines?

[DeJohn]

The differences between National V and National VI emission standards are as follows: Different emission standards: The National VI emission standard is more than 30% stricter than National V. Excluding the influence of working conditions and testing, gasoline vehicles' carbon monoxide emissions are reduced by 50%, total hydrocarbons and non-methane hydrocarbons emissions are reduced by 50%, and nitrogen oxide emissions are reduced by 42%. Different implementation times: The National V standard was implemented nationwide on January 1, 2017. National VI has been implemented since July 1, 2019. Different principles: During the National V phase, diesel and gasoline vehicles had different emission standards, but National VI adopts a fuel-neutral principle, meaning the emission limits are the same regardless of the fuel type. Different issuing departments: The National V standard was issued by the Ministry of Environmental Protection. The National VI standard was issued by the Ministry of Environmental Protection and the General Administration of Quality Supervision, Inspection and Quarantine. Different letter representations: National V is represented by "V," while National VI is represented by "VI." Different monitoring requirements for plug-in hybrid electric vehicles: Compared to National V, National VI has improved monitoring requirements for plug-in hybrid electric vehicles, including energy storage systems, thermal management systems, brake regeneration, drive motors, generators, and other regulations. Different prices: National VI vehicles are equipped with more components than National V vehicles. Additionally, automakers incur extra costs from vehicle declaration tests and production, leading to significantly higher prices for National VI vehicles compared to National V. Different scrapping timelines: Although the government has abolished the scrapping age limit, older vehicles may be banned from roads, effectively rendering them scrapped. For example, a National V vehicle purchased in January 2019 and a National VI vehicle purchased at the same time may both have a 15-year registration, but their actual usage will differ. For instance, National III vehicles from 2010 and National IV vehicles from the same year can still operate in Beijing, but as more cities impose restrictions, many older vehicles become practically scrapped. Thus, even for vehicles of the same year, their usable lifespans differ. National V standards are as follows: Gasoline vehicles must not emit more than 1,000 mg of carbon monoxide per kilometer driven. They must not emit more than 68 mg of non-methane hydrocarbons, 60 mg of nitrogen oxides, or 4.5 mg of PM (particulate matter) per kilometer driven. National VI has two standards: National VIa and National VIb, as follows: National VIa standards: Gasoline vehicles must not emit more than 700 mg of carbon monoxide, 68 mg of non-methane hydrocarbons, 60 mg of nitrogen oxides, or 4.5 mg of PM per kilometer driven. National VIb standards: Gasoline vehicles must not emit more than 500 mg of carbon monoxide, 35 mg of non-methane hydrocarbons, 35 mg of nitrogen oxides, or 3 mg of PM per kilometer driven. Under the National VI emission policy, although National V vehicles are not currently restricted from 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 vehicle's depreciation after paying off the loan represents the net profit during that period. A higher residual value means more profit for the owner. From this perspective, National VI vehicles, with longer lifespans and greater road access, offer more advantages.

[MelanieFitz]

I've been driving trucks for twenty years, and I clearly felt the engine's temperament change when switching from China V to China VI. China VI vehicles are particularly picky about fuel—you must fill up at reputable gas stations, as fuel from small workshops can easily clog the particulate filter in the exhaust pipe. Manufacturers packed more purification devices into the exhaust system, like upgrading the catalytic converter to a dual-layer one, and the piping under the car is more complex than a spider's web. The most annoying part is that the vehicle now self-checks emissions, with several extra sensors on the exhaust pipe—if you're not careful, the fault light comes on. Old Wang at the repair shop says China VI engines are tuned to be gentler; stomping on the gas doesn’t give the same kick as China V, but in the long run, it’s definitely more eco-friendly.

[DeNadia]

My friend in auto repair told me that the China VI engine is essentially a triple 'tight curse' on the China V: first, they added a sensor to monitor nitrogen oxides in real-time, then wrapped the exhaust pipe in a 'sweater' called GPF particulate filter, and finally completely rewrote the engine's computer program. These modifications make the car feel like running with a mask on—power response lags a bit, especially during cold starts when you can hear the exhaust pipe rattling during regeneration. The worst part is the maintenance cost; even replacing an oxygen sensor wire can cost over a thousand yuan, and diesel vehicles require regular attention to the urea tank, making it more demanding than raising a pet.

[Eleanor]

When I bought the National V (China 5) car back then, the 4S store fooled me by saying it could last ten years. But as soon as the National VI (China 6) standard came out, its value immediately dropped by 20,000 yuan. In fact, the most obvious difference of the National VI engine is that the exhaust pipe is thicker, equipped with a two-stage catalytic converter and a particulate filter. During my last maintenance, I noticed an additional 'active regeneration' item on the repair list. The technician said it's a procedure to burn off carbon deposits. Driving a National VI car in the city is actually fuel-efficient, but the engine fault light keeps coming on for no reason. The 4S store charges 300 yuan just to clear a fault code with their computer.

[LeJude]

According to the parameters released by the Environmental Protection Agency, China 6 is much stricter than China 5: the hydrocarbon limit is halved, nitrogen oxides are reduced by another 40%, and even 99% of the suspended particles in the exhaust must be filtered out. To achieve this, automakers have recalibrated the engines to ensure more complete combustion of gasoline in the cylinders. The trade-off is a torque loss of about 10% at low RPMs, making high-speed overtaking slightly more challenging. Our test team measured that the China 6 version of the same model accelerates 0.8 seconds slower than the China 5 version, but the optimized start-stop system has improved smoothness.

[VonPeter]

My cousin works at an engine factory and mentioned that the China VI engines are equipped with six core upgrades: fuel injectors precise to the nanometer level, alloy pistons capable of handling lean combustion, turbochargers that withstand 900°C high temperatures, a dual-channel EGR exhaust gas recirculation system, a temperature-controlled water pump with active adjustment, and an onboard computer capable of self-diagnosis. These modifications have reduced the air-fuel ratio control error from ±5% to ±0.5%. Simply put, the engine now operates like it's equipped with a microscope, squeezing every drop of fuel to its maximum potential. The downside is that the maintenance interval has been shortened from 10,000 kilometers to 7,500 kilometers.