On-board real life emission measurements on a 3 way catalyst gasoline car in motor way-, rural- and city traffic and on two Euro-1 diesel city buses

On-board emission measurements were performed on a Ford Escort 1.3 l gasoline car and on two Van Hool A300D turbo diesel buses. When compared to the limit values of the 91/441/EEC directive, the TWC car yields lower emissions in motor way traffic and values are about equal in rural traffic. However, in the city with a hot start the CO- and HC + NOx-emissions amount to 5.7 and 2.3 g/km, that is double the limit values. Respectively, 16 and 4.2 g/km are measured with a cold start which is five and four times the limit values. The Euro-1 diesel city buses, that are tested during the regular bus service, have on-the-road emission intervals for CO, HC and NOx of respectively 7–8, 0.9–1.1 and 18–23 g/km. These transient emissions, transformed to g/kWh, are about 1, 0.5 and 1 to 1.5 times the Euro-1 limit values, respectively. The car to bus comparison of hot start city emissions in g/km shows that CO and HC are about equal, whereas NOx is 30 times higher for the bus. However, in g/passenger km, CO and HC-emissions are respectively 30 and 50 times lower for the bus, while NOx-emission is equal.