Idling Vehicle Emissions and Fuel Consumption in Urban Use: Influence of the Stop&Start Technology

Engine idle stop-start (S&S) is a technology which allows a vehicle to automatically turn off the internal combustion engine (ICE) when the vehicle has a rest and restarts the ICE when the driver applies pressure to the accelerator or releases the brake. Stop-Start system originated in Europe to save fuel during the type-approval New European Driving cycle (NEDC) because almost 25% of its driving time is in idling conditions. In real use, the largest benefits of S&S systems in vehicles result in urban areas where frequent stops are common. To evaluate the benefits of such systems in terms of fuel saving and emission reduction, an experimental campaign has been realized in Napoli. Three cars have been instrumented by using a Portable Emission System (PEMS) and driven along urban routes. Carbon dioxide (CO₂), carbon monoxide (CO) and nitrogen oxides (NOX) have been evaluated for each trip in function of the average time spent stopping at traffic lights or for traffic conditions, as a percentage of a trip's duration.