Abstract: To investigate the characteristics and evolution of particle number (PN) emissions from gasoline vehicles at different stages of use, two representative gasoline vehicles were selected for PN emission tests under both the WLTC and RDE driving cycles at various mileage intervals. The results show that as mileage increases, vehicle PN emissions exhibit a trend of first rising and then stabilizing. When the mileage is less than 10,000 km, PN emissions are relatively high, which is likely attributed to incomplete engine break-in and unstable conversion efficiency of the aftertreatment system, particularly the gasoline particulate filter (GPF). When the mileage ranges from 10,000 to 40,000 km, PN emissions increase significantly. When the mileage exceeds 40,000 km, PN emissions tend to stabilize, suggesting that both engine performance and GPF conversion efficiency have reached a steady state.Furthermore，depth analysis factorsof influencing PN emissions reveals that under the WLTC cycle, high PN emissions occur during cold-start and deceleration phases. Under the RDE cycle, frequent vehicle starts/stops and high-load acceleration are the primary causes of elevated PN emissions. During the WLTC test, urban driving phase accounts for more than 70% of total PN emissions, while the extra-high-speed phase contributes 2%–20%. In contrast, PN emissions during suburban and highway phases are relatively low. Moreover, significant differences exist between PN emission results obtained under WLTC and RDE conditions. Relying solely on WLTC test results cannot accurately reflect real-world particle emissions. Therefore, greater emphasis should be placed on research and regulation of vehicle PN emissions under RDE conditions.

Key words: gasoline vehicle, mileage, PN emissions, influencingfactors, WLTC, RDE