Abstract:To reflect the emission level of light-duty vehicles more comprehensively and realistically, it is necessary to consider the cold-start emissions of vehicles in real driving emission (RDE) tests. For this purpose, a light-duty gasoline vehicle complying with China Ⅵ emission standards was selected to complete eight RDE tests, and its cold-start emissions were included in the total urban emissions evaluation. The results show that the contributions of CO, NOx, and PN emissions from the cold-start trips to the total urban emissions are 28.3%, 31.9%, and 39.8%, respectively. In the full cold-start trip, CO and CO2 emissions are significantly correlated with average coolant temperature, while NOx and PN emissions are strongly correlated with average vehicle speed. Additionally, the cold-start emission results under RDE tests are quite different and closely related to the dynamic parameter v·apos (velocity times positive acceleration) in the first 50 seconds of cold-start. It is recommended that the dynamic parameters at the initial stage of cold-start (e.g., the first 50 seconds of cold-start) should be strictly limited when amending the RDE test procedure considering cold-start emissions.