LAUSR

Abstract The aim of the study was to investigate the real driving emissions of two vehicles widely used as private means of transport in Italian cities: a Euro 4 gasoline passenger car and a Euro 3 scooter. Exhaust emissions of two and four wheel vehicles were characterised over three urban routes in Naples. On-board measurement of CO, NOx, CO2 and fuel consumption of the car was made with a Portable Emissions Measurement System (PEMS); exhaust emissions of NOx and fuel consumption of the scooter were measured in the laboratory, reproducing speed profiles acquired on the road on a chassis-dynamometer. In both cases, vehicle spatial position was acquired by Global Positioning System (GPS) at a frequency of 10 Hz. Real vehicle speed and acceleration together with road gradient were used to evaluate the specific power of the vehicle (VSP) and the results were modelled so as to correlate emissions with driving activities. Specific emissions and fuel consumption were also analysed as a function of road gradient. The most critical results for the car concerned NOx emissions which greatly exceeded the type-approval limit, and real driving of the scooter involved a significant increase in fuel consumption. For both vehicles, positive road gradient greatly influenced fuel demand, while NOx and CO emissions were considerably reduced on downhill stretches.