Browse Publications Technical Papers 2020-37-0034

A Methodology for Monitoring Real-World CO2 Emissions Compliance in Passenger Vehicles 2020-37-0034

The road transport CO2 emissions reduction scheme in the European Union foresees mandatory targets for passenger vehicles. However, several studies have shown that there is a divergence between official and real-world values that it could be up to 40% in the NEDC. The introduction of the WLTP was expected to curb this divergence, but it is uncertain whether it can fully address the problem. In order to address this issue, future legislation aims at monitoring on-road fuel consumption and subsequently CO2 emissions by utilizing on-board fuel consumption meters. The current study investigates a monitoring approach that obtains and normalizes on-road vehicle operation data and estimate CO2 emissions through vehicle simulation. The first step is to create the vehicle’s engine fuel consumption map, based on laboratory vehicle measurements in order to use it as reference data. Subsequently, a methodology is developed to produce the vehicle’s engine map from signals retrieved through the OBD port in order to emulate data availability under a monitoring scheme. The methodology to derive the vehicle’s engine fuel consumption map includes an approach that normalizes the data by removing the effect of ambient conditions and technologies, such as the air-conditioning. Accordingly, the methodology is validated based on reference data. In the following step, within the context of a large-scale monitoring scheme, a series of OBD loggers were installed on several private cars to monitor daily vehicle operation. The retrieved OBD data is used to produce the engine fuel consumption maps and to develop the respective vehicle simulation models. All necessary simulation input data for the vehicles’ components, such as gearbox, are selected based on generic data and tools. In the last step, the fuel consumption of the vehicle is simulated over the WLTP and the results are compared to the measured and the official WLTP values.


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