Exhaust emissions were determined from a fleet of some 50 cars that have been in normal private ownership service in Finnish driving conditions. These represent typical Nordic climate with strongly varying ambient temperatures between summer and winter months. All cars were petrol fuelled, and had an up-to-date emissions control system based on a three-way catalytic converter. Tested vehicles represented model years 1990 to 1996. They had odometer readings at the time of testing ranging from a low of 10,000 km up to a high of 373,000 km. The emissions performance was assessed using mainly US FTP75 urban driving schedule, but a small subset of vehicles were tested using the latest European test cycle ("EC 2000") with modified start procedure. These vehicles were also a subject to a project on the implications of service on in-use emission. All testing was performed at normal ambient temperatures (+22...23 degrees C). The paper presents an assessment of typical emissions performance as a function of distance driven expected from normal TWC-cars that have been in day-to-day use under sometimes quite rigorous Nordic driving conditions. It appears, however, that even in these ambient conditions with many cold-starts, acceptable durability is maintained. This judgement was based on the perceived degradation in the functioning of the emission control systems, which was close to the deterioration described in those assigned deterioration factors that are given in the legislation for projecting the standards over the required durability range. The results present also information on the actual emission rates of typical in-service passenger cars that can be used, e.g. in emission inventory calculations. (A)
Abstract