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CO, CO2, HC, CH4, NOx, N2O emissions as well as emissions of 10 PAHs and fuel consumption were measured on 10 conventional petrol-engined passenger cars, 10 vehicles equipped with 3-way catalysts, and 5 diesel-engined vehicles over a great number of driving cycles under hot or cold start conditions: the 2 standardized European and American cycles, Highway cycle, 4 hot cycles representative of real-world driving conditions, and 3 representative mini-cycles, which have been repeated 15 times after a cold start. Simultaneously, water and oil temperatures were measured to assess engine temperatures. The analysis of the results enabled the monitoring of emission and temperature changes with time for various kinematic types. The limit of hot temperature, the distance travelled under cold start conditions (over about 6 km), the excess emission rates under cold start conditions, and absolute excess emissions after a cold start could be thus determined.

For a particular type of vehicle, fuel consumption and pollutant emission rates are mainly a function of the vehicle's use (journey type, frequency, etc…), and of the vehicle's operating conditions (speed, engine speed, rates of acceleration, temperature conditions, etc…), and depend on both the traffic conditions and the individual behaviour of the driver. Thus, a realistic assessment of emissions, pollution reduction methods and the effectiveness of emission control technologies cannot be carried out without taking into account the actual operating conditions of the vehicles. For that reason, a project has been carried out as part of the EC DRIVE programme to measure engine and vehicle operating conditions during normal driving. 58 private cars were equipped with sensors and data acquisition systems to record details of their use by their owners, each over a period of about one month.

In order to assess accurately the influence of acceleration, a study was carried out to determine the most important vehicle parameters that influence the emissions and fuel consumption of passenger cars. Emission measurements have been conducted in three laboratories in France, Germany and UK on the basis of 14 driving cycles specially designed to cover the whole range of vehicle speed and acceleration in urban traffic. 150 vehicles, representing the European 1995 fleet, were tested, and the emissions of CO, HC, NOx and CO2 and the fuel consumption continuously recorded. Average unit emissions are presented as a function of average speed and vehicle type. Subsequently, a model was developed to calculate emissions during an urban trip as a function of the vehicle type and its instantaneous speed and acceleration. The model is given in the form of a two dimensional function with the variables speed and speed times acceleration for all vehicles types.

Exhaust concentration (in ppm) and emission (in g/km) measurements (for CO, HC, NOx and CO2) will be compared over a sample of 49 as-received gasoline engined vehicles, in which 10 were equipped with a 3-way catalyst, in order to assess the viability of rapid methods of emission measurements. The exhaust gas concentrations at the tailpipe were measured from 15 engine operating conditions (6 engine speeds, 4 gear choice). The emission measurements were performed using European standardized cycles ECE15 and ECE15+EUDC and 4 specific actual cycles, representative of the various vehicle usages. The results obtained are not encouraging as regards the interest of concentration measurements at the tailpipe, even with optimum engine operating conditions: the relationship between exhaust concentrations and actual or standardized emissions is always very poor. The best correlation depends on the pollutant, but could be for 3000 rpm in neutral.

This study aims at analyzing light vehicle traffic in France and at characterizing it by a set of speed profiles. A new approach is proposed introducing the notion of kinematic sequence and using different methods of data analysis. The first objective is to get satisfactorily summarized information on the structure of vehicle displacements. A set of data, recorded from an instrumented passenger car fleet for the EUREV study, is analysed with data analysis processing. The great variety of the speed profiles collected means that the study is representative of the actual use of cars in France. Four sequence categories which feature specific types of traffic are shown. Consequently these sequences should lead to the measuring of fuel consumption and pollutant emissions representative of the actual uses, under appropriate laboratory conditions.

The emissions (CVS)) and energy consumption of a representative sample of 28 gas-driven passenger cars are measured on different driving cycles: at 7 constant speeds from 0 to 120 kph, ECE 15, two cycles adapted to the tunnel traffic and 10 statistically representative new cycles including real speed profiles as well as random gear ratios adapted to each vehicle according to its engine speed and acceleration. Some of the 28 driving cycles were driven before and after tuning, with cold and hot start. The main influence of the average cycle speed and of the speed profiles of the cycles, are shown: constant speeds and ECE 15 results are lower by 15 to 50 %. The great influence of transient speeds is also shown. CO, HC, NOx emissions and energy consumption are respectively 140, 200, 8 and 50 % higher with cold start than with hot stard.