Many territorial entities are seeing their prerogatives and regulatory powers enhanced with new “instruments” intended to foster the development of ecomobility. Taking as its focus the way that individuals make decisions about transportation modes, EM3 is a transport model designed to simulate the potential impacts of different regulatory measures on the travel practices of inhabitants of an urban area and on the resulting pollutant emissions. One of the originalities of this model is that it emphasises the behavioural dimension, taking the view that this dimension is a parameter whose effects on the outputs of transportation models are currently unknown and possibly not insignificant. Alongside the standard, it models a socio-psychological behavioural approach and a sociology-based approach. The comparison of the three behavioural approaches shows substantial differences in the outcomes observed, whether globally or at the level of local indicators. In addition, the results indicate that the effects of a measure such as a Low Emission Zone extend beyond the specific scope of the geographical area concerned, and can also contribute to strengthening or weakening existing socio-spatial inequalities. We end this chapter by presenting the finality of our approach which aims to support the planning decisions of territorial collectivities thanks to the use of an experimental platform that can shed light on the impacts of various parameters relating to the territorial specificities and the behavioral complexity of users.