Impact of driving style and road grade on gaseous exhaust emissions of passenger vehicles measured by a Portable Emission Measurement System (PEMS)

Abstract

Motivated by the upcoming Euro-6c regulation including Real Driving Emissions (RDE), the present study addresses the impact of different driving styles and route characteristics on on-road exhaust emissions. Gaseous emissions of two Diesel test vehicles (Euro-5 and Euro-6) were measured using a Portable Emission Measurement System (PEMS) on an RDE compliant test route.The driving parameters relative positive acceleration (RPA), mean positive acceleration (MPA) and v∗apos95 allowed a favorable classification of different driving styles. The comparison of driving parameters for normal PEMS trips with reference data obtained from the World harmonized Light-duty Test Cycle (WLTC) and from Field Operational Tests (FOT) indicated a good representation of normal driving. Severe driving led to elevated CO2 and NOx emissions as compared to normal trips while CO and HC did not allow a distinct classification of different driving styles.Route characteristics of four different routes were investigated applying the parameter cumulated altitude gain using Google Elevation data. The distance specific NOx emissions were in the same range for trips with comparable driving dynamics on routes with similar cumulated altitude gain. Based on repetitive measurements the road grade was calculated within 100m segments. CO2 and NOx emissions measured by a PEMS showed a linear increase with road grade. Larger emissions at higher road grades could be explained by more frequent high engine load points. In this study cumulated altitude gain and road grade were directly correlated to emissions measured by the PEMS and the step from 0 to 5% road grade led to a CO2 increase of 65–81% and a NOx increase of 85–115%.