Study on Real Road Driving Emission Characteristics of Light-Duty Gasoline Vehicles

In November 2018, the real driving emissions (RDE) package 4 of European Commission regulation was released, and the RDE test method was improved, the data processing method and cold start data processing were different from the China 6 light-duty vehicle standards. In some congested cities of China, the average speed of vehicles during morning and evening rush hours is lower than that in the RDE urban phase. In order to evaluate the impact of data processing methods, cold starting data processing and congestion conditions on RDE test, the real driving emissions from 5 light-duty GDI gasoline vehicles were measured on the GB6 RDE test route and the typical urban test route respectively. It was found that CO, NOx and PN specific emissions based on EU package 4 data processing methods were 22, 46 and 29% higher than the moving average window method results of GB6. For the CO, NOx and PN emissions, the reserved cold starting test results of 5 test vehicles are 18, 42 and 15% higher than the results excluding cold starting data. For the vehicle A, CO and PN emissions under the typical urban road are greater than GB6 RDE road test emissions, as NOx and THC emissions are roughly the same. The CO, THC and PN emission results increased in congested road conditions, which were 2.8 times, 2.9 times and 3.5 times higher than those in the condition of smooth road. Emissions of CO, THC and CO2 along the two test journeys show a decreasing trend with the increase of average speed, as PN emissions show an increasing trend with the increase of average positive acceleration of the travel. NOx emission decreases with the increase of average positive acceleration of the travel.