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This study aims to measure and analyze unregulated compound emissions for two Euro 6 diesel and gasoline vehicles. The vehicles were tested on a chassis dynamometer under various driving cycles: Artemis driving cycles (urban, road, and motorway), the New European Driving Cycle (NEDC) and the World Harmonized Light-Duty Test Cycle (WLTC) for Europe, and world approval cycles. The emissions of unregulated compounds (such as total particle number (PN) (over 5.6 nm); black carbon (BC); NO; benzene, toluene, ethylbenzene, and xylene (BTEX); carbonyl compounds; and polycyclic aromatic hydrocarbons (PAHs)) were measured with several online devices, and different samples were collected using cartridges and quartz filters. Furthermore, a preliminary statistical analysis was performed on eight Euro 4-6 diesel and gasoline vehicles to study the impacts of driving conditions and after-treatment and engine technologies on emissions of regulated and unregulated pollutants. The results indicate that urban conditions with cold starts induce high emissions of BTEX and carbonyl compounds. Motorway conditions are characterized by high emissions of particle numbers and CO, which mainly induced by gasoline vehicles. Compared with gasoline vehicles, diesel vehicles equipped with catalyzed or additive DPF emit fewer particles but more NO and carbonyl compounds.

This paper focuses on CO 2 and regulated pollutants (NO x , HC, CO, PM) emitted by eight Euro 4-6 gasoline and diesel vehicles with six different technologies. The emission factors were repeatedly measured on a chassis dynamometer bench using Artemis Urban with cold and hot start, Road and Motorway, WLTC and NEDC driving conditions. The influence of driving conditions and approved driving cycles on pollutant emissions was also investigated. The measured emission factors for regulated compounds were compared to the corresponding emission factors of the COPCETE emission model developed by the French Ministry of Ecology. The results indicate that the NEDC cycle, used for type-approval of emissions of regulated compounds, leads to underestimation of CO 2 (9-23%) and NO x (1.2 to 2 times) emissions and overestimation of CO and HC (2 to 5 times) in relation to the Artemis cycles, which are real-world simulation driving cycles. The WLTC cycle for the worldwide harmonization of vehicle emissions shows similar HC, NO x and CO emissions with the Artemis average cycle within uncertainty of the measurements. The NO x emissions measured were 1.6 to 8 times greater than the type-approval limits. These high NO x emissions produced by all the diesel vehicles tested under real-world driving conditions could serve as particle precursors and increase secondary organic aerosol formation. They are also indicative of the significant cause for concern regarding urban air quality and the increase in the portion of Euro 5 and 6 diesel vehicles in France's vehicle fleet. Regarding emission factor assessments, the emission levels measured are overall in fair agreement with the COPCETE predictions within uncertainties for CO 2 and regulated pollutants. Updating the database is vital in order to be able to produce more representative emission factors and better evaluate the health and environmental effects from vehicle emissions.

Dilution and temperature used during sampling of vehicle exhaust can modify particle number concentration and size distribution. Two experiments were performed on a chassis dynamometer to assess exhaust dilution and temperature on particle number and particle size distribution for Euro 5 and Euro 6 vehicles. In the first experiment, the effects of dilution (ratio from 8 to 4000) and temperature (ranging from 50 °C to 150 °C) on particle quantification were investigated directly from tailpipe for a diesel and a gasoline Euro 5 vehicles. In the second experiment, particle emissions from Euro 6 diesel and gasoline vehicles directly sampled from the tailpipe were compared to the constant volume sampling (CVS) measurements under similar sampling conditions. Low primary dilutions (3-5) induced an increase in particle number concentration by a factor of 2 compared to high primary dilutions (12-20). Low dilution temperatures (50 °C) induced 1.4-3 times higher particle number concentration than high dilution temperatures (150 °C). For the Euro 6 gasoline vehicle with direct injection, constant volume sampling (CVS) particle number concentrations were higher than after the tailpipe by a factor of 6, 80 and 22 for Artemis urban, road and motorway, respectively. For the same vehicle, particle size distribution measured after the tailpipe was centred on 10 nm, and particles were smaller than the ones measured after CVS that was centred between 50 nm and 70 nm. The high particle concentration (≈10 6 #/cm 3) and the growth of diameter, measured in the CVS, highlighted aerosol transformations, such as nucleation, condensation and coagulation occurring in the sampling system and this might have biased the particle measurements.