We always habitually regard environmental protection as a 'technological competition' - whoever has electric vehicles farther away and hydrogen powered vehicles landing faster will win the future. But is there a possibility that the true winner of this competition is actually hidden in an inconspicuous tin can?

You may not have heard of it, but it's right in your or your friend's car: the metal block hidden in the middle of the exhaust pipe, dusty and like a muffler, called a particulate filter (GPF or DPF). Its task is simple: to intercept the black smoke, which is small carbon particles, emitted by the engine. Sounds like a 'patched' solution, right? But after flipping through almost all emission standards from Euro I to China VII, from the US EPA to Japan's later low pollution vehicle regulations, I suddenly realized one thing: this' patch 'may never be removed.

Why? Because the inherent contradiction of internal combustion engines has never been truly resolved.

We always think that the stricter the emission standards, the closer we are to 'zero emissions'. But the reality is that the stricter the standards, the more 'involution' the technology becomes. For example, China VI B and Europe VI D have already limited the number of particulate matter (PN) to 6 × 10 ¹¹ per kilometer. What is this concept? It's equivalent to burning one liter of oil, which can only release visible particles less than a grain of salt. But as long as the oil is still burning, even if it is highly efficient, carbon nuclei will be generated in the moment of incomplete combustion. Especially for in cylinder direct injection engines, the explosive growth of tiny particles cannot be avoided during cold start and rapid acceleration.

So, the particle trap became the only option for "safety net". You can pile up black technology on the combustion system - high-pressure common rail, 350Bar injection pressure, variable valves, cooling EGR - but regulatory agencies simply don't believe you can 'burn it clean'. They only recognize the result: the exhaust pipe outlet must be clean. So even if your engine tuning is perfect, without GPF, you can't even pass the laboratory certification.

It's like an exam where the invigilator says, 'I don't care how hard you try, I only look at the final score on the paper.' So, even if you understand all the knowledge points, you have to bring a draft paper and a verification book - GPF is the 'verification book' to prove that you haven't cheated.