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Motor fuels are today increasingly blended with oxygenate components to reduce global CO2 emissions. Among these components, biomass-derived ethanol is very popular for spark ignition engine operation as it is not only a renewable source of energy, but it also allows to increase the engine power and thermal efficiency. Indeed, ethanol has the advantage of a high latent heat of vaporization leading to the so-called “cooling effect” which allows to increase the air-mass flow rate in the engine while reducing the charge temperature. This last property of ethanol combined with its high octane index make the engine less sensitive to knock. Then, although ethanol is characterised by high combustion speeds, optimal values of spark advance can be maintained on a larger range of engine operating conditions and high compression ratios as well as increased levels of downsizing can be used, all these aspects contributing to improve fuel consumptions.

In order to meet the CO₂ challenge, today a wide variety of solutions are developed in the automotive industry such as advanced technologies (downsizing, VVA, VCR), new combustion modes (HCCI, stratified and lean combustion), hybridization, electrification or alternative fuels. Furthermore, couplings between these solutions can be envisaged, increasing considerably the number of degrees of freedom which have to be accounted for in the development of future powertrains. Consequently, for time and cost reasons, it is not obvious to evaluate and optimize the full potential of new concepts only by the mean of experimental investigation. In this context, system simulation appears as a powerful and relevant complement to engine tests for its flexibility and its high CPU efficiency. This paper focuses on the development of a methodology combining both simulation and experimental tools to quantify the interest of innovative solutions in the very first steps of their development.