ON-BOARD EMISSION AND FUEL CONSUMPTION MEASUREMENT CAMPAIGN ON PETROL-DRIVEN PASSENGER CARS

Realistic emission and fuel consumption rates of petrol-driven cars we re determined by on-the-road experiments in 1995. A validated, in-hous e developed, on-board measuring system was used. Six three-way catalys t (TWC) cars and one carburetted non-catalyst car were measured. The e ffects of road type, driving behaviour and cold start on CO, HC and NO x emissions and fuel consumption were analysed. In real traffic situat ions, emissions for TWC cars were found to be at least 70% lower than for the non-catalyst car. For TWC cars, emissions decreased across the board from city to rural and motorway traffic. Without a catalyst, mo torway traffic resulted in the highest NOx emissions. Compared to norm al driving, aggressive driving gave emissions which were up to four ti mes higher. Except for NOx, calm driving resulted in lower emissions s till. Comparable fuel consumption rates were obtained from normal and calm driving. Those from aggressive driving were higher, by as much as 40% in city traffic. Cold starts resulted in significantly higher CO and HC emission values than hot starts. These differences were less pr onounced for NOx. Emissions from TWC cars were higher than generally e xpected, compared to the European emission limit values (91/441/EEC) a nd the emission factors used in Flanders and the Netherlands (Klein,19 93) for the national emission inventories. Low-emitting cars during th e emission test on a chassis dynamometer, as prescribed by the 91/441/ EEC directive, did not necessarily give low emissions in real traffic situations. (C) 1997 Elsevier Science Ltd.