What are the differences between National III and National IV vehicles?

[LaLyla]

The differences between National III and National IV vehicles: 1. Different markings: National III vehicles are marked as 'National III'; National IV vehicles are marked as 'National IV'. 2. Different numbers of processing systems: National III vehicles have one muffler; National IV vehicles have two mufflers. 3. Different traffic restrictions: National III vehicles can enter within the Sixth Ring Road; National IV vehicles are not subject to any restrictions. 4. Different engines: National III vehicles use direct injection in the cylinder with a large pump fuel supply method; National IV vehicles use electronic injection in the cylinder with a common rail fuel supply method. National III vehicles comply with China's third-stage vehicle emission standards. National IV vehicles comply with China's fourth-stage vehicle emission standards.

[DeEmma]

I work in auto repair, and the main difference between China III and China IV vehicles lies in the exhaust system. China IV vehicles have an additional automatic diagnostic system called OBD, which triggers a fault light when emissions exceed standards, and the exhaust pipe also includes an adsorption device. The most obvious difference is the manufacturing year gap—most vehicles produced between 2007 and 2011 are China III, while those after 2011 are mostly China IV. After installing a urea system, China IV vehicles can reduce fuel consumption by about 5%, but maintenance costs are significantly higher—replacing a catalytic converter can cost three to four thousand yuan. During inspections, many China III vehicles barely pass the emissions test, as the allowable limits are nearly double those for China IV. Many cities now restrict China III diesel vehicles from entering urban areas, so if you're hauling goods, I recommend buying a used China IV vehicle directly.

[LaRobert]

Having researched emission policies for over a decade, the China IV standards reduced pollutant limits by nearly 60%. Diesel vehicles underwent the most significant changes with the addition of SCR urea injection systems, which notably improved nitrogen oxide treatment. Gasoline vehicles switched to electronically controlled fuel injection, and three-way catalysts were enhanced with precious metal coatings. Most crucially, China IV marked the first requirement for real-time onboard diagnostic monitoring, essentially equipping vehicles with an environmental doctor. Currently, there are subsidy policies for phasing out China III vehicles, but buyers should note that diesel vehicles manufactured before July 2013, even if labeled as China IV, might actually be modified from China III technical platforms. When purchasing used vehicles, it's essential to check the engine model.

[LincolnDella]

Having driven diesel light trucks for ten years, the difference between National III and National IV vehicles is night and day. National IV trucks have a delayed throttle response, feeling like they're being held back when accelerating. However, they're more fuel-efficient on long hauls—my National IV OMC saves 1.5 liters per 100km compared to the National III era. The biggest headache is the AdBlue consumption, needing a refill every 2,000 km, and the nozzles are prone to crystallization clogging in winter. Maintenance costs are staggering—last time, replacing the AdBlue pump cost me 4,800 RMB. While National III vehicles don’t have these issues, environmental inspections are getting stricter, and many cities no longer issue operating permits for diesel National III trucks.

[CarolineFitz]

After careful comparison when purchasing a car, China IV vehicles are about 10,000 yuan more expensive on average than China III used cars, but they're more cost-effective in the long run. Their emission test pass rate is higher, and they basically have unimpeded access in cities with driving restrictions. The technological upgrades are quite substantial: increased fuel injection pressure for more complete combustion, installation of diesel particulate filters, and recalibration of the engine ECU program. However, be cautious with transition period models from 2011-2013, as some China III engines were reprogrammed to masquerade as China IV - checking the vehicle conformity certificate is the most reliable method. Currently, China III vehicles over six years old require additional OBD inspections during annual checks, with an exhaust emission failure rate exceeding 30%.

[RyderLynn]

At the testing station, the tailpipe emission test has been conducted for six years. The emission limit for CO in China III gasoline vehicles is 1.0g/km, while for China IV, it drops directly to 0.5g/km. In practice, there's a difference of two orders of magnitude between China III and China IV vehicles: pre-2013 China III vehicles often barely pass at the 1.0 limit, whereas China IV vehicles are mostly below 0.3. The difference is even more pronounced for diesel vehicles, as China IV models must be equipped with a DPF (Diesel Particulate Filter). The most critical issue is the new annual inspection regulations, which now require China III vehicles to undergo a loaded deceleration test, and many older vehicles fail to meet the power requirements. Last year, 80% of the China III light trucks phased out at our station were due to failing either the emission or power tests.