Development of a Template Model and Simulation Approach for Quantifying the Effect of WLTP Introduction on Light Duty Vehicle CO ₂ Emissions and Fuel Consumption

The paper describes the development of a modelling approach to simulate the effect of the new Worldwide harmonized Light duty Test Procedure (WLTP) on the certified CO₂ emissions of light duty vehicles. The European fleet has been divided into a number of segments based on specific vehicle characteristics and technologies. Representative vehicles for each segment were selected. A test protocol has been developed in order to generate the necessary data for the validation of the vehicle simulation models. In order to minimize the sources of uncertainty and the effects of flexibilities, a reference “template model” was developed to be used in the study. Subsequently, vehicle models were developed using AVL Cruise simulation software based on the above mentioned template model. The various components and sub-modules of the models, as well as their input parameters, have been defined with the support of the respective OEMs. Specific strategies have been defined for the implementation of individual technologies affecting fuel consumption such as Start-stop, Brake Energy Recuperation, and Variable Valve Actuation etc. Each vehicle model was validated comparing simulations with measurements for both WLTP and NEDC, achieving accuracies better than 2.5% on the absolute end values for each cycle, and better than 2 g CO₂/km on the difference between the two cycles with respect to the measurements. Finally, a first quantification of the effect of WLTP introduction on CO₂ emissions and fuel consumption of the specific vehicles is attempted.