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Besides the further reduction of the harmful gaseous emissions (HC, CO and NOx) to reach upcoming emission limits, the discussion on lowering the CO₂ emissions is omnipresent. From engine development point of view further optimization of the stoichiometric-operated gasoline engine as well as the introduction of lean-operated engines are the main development trend. The emission control system can support the engine development by dedicated catalyst technologies as presented in this paper. A new family of TWC technologies offers to tune the catalyst system to the engine performance and the back pressure requirement - which helps to reduce CO₂ emissions. In addition these technologies show improved performance in HC, CO, NOx light-off, and in CO and NOx conversions under dynamic conditions - this again can positively impact the CO₂ emissions as less harsh heating strategies for cold start is required.

China 6 emission legislation was finalized in 2018 and the full implementation nationwide is postponed to 2021 due to COVID-19. It is foreseen that the post China 6 legislation will have more stringent primary and secondary emission requirements including further reduction of nitrous oxide (N2O) emissions and likely to include limits on ammonia (NH3) emissions. This study investigated the secondary emissions (i.e. N2O and NH3) of a variety of China 6 production gasoline vehicles operating under the worldwide harmonized light vehicles test cycle (WLTC) and random test standardized aggressive (RTS 95) cycle. It was found that N2O emissions were less than 5 mg/km on all these vehicles, far below the current China 6 limit (20 mg/km), however NH3 emissions varied from 2 to 48 mg/km among the production vehicles. The mechanisms of N2O and NH3 formation and their correlation with primary emissions were also investigated.