In this article we propose a decision-aid tool for local authorities to plan and implement their transport policies. We set out sustainable-mobility scenarios that depend on the geographical contexts of different areas based on 50 mobility offers, including active modes, car-sharing, public transport, etc. To do so we appeal to a multi-criteria decision analysis (MCDA), relying on an original two-step assessment method. We first use the diviz decision-aid tool to obtain a global score for each mobility offer, on the basis of 18 criteria covering the three pillars of sustainable development (economy, environment and society) and the concerns of the mobility actors themselves (historical actors, newcomers, public authorities and users). This step supports mobility management by local authorities, as it makes it possible to rank mobility offers by type of area. Second, we use the MICMAC decision-aid tool to construct the influence and dependency relationships between our 18 criteria. The aim of this step is to identify some relevant criteria that are determinant in a prospective or strategic analysis, in order to consider what could be a development scenario for the future of everyday mobility in various areas. As alternatives to personal car are rare, we apply this two-step method to the case of low-density areas, and find highlighting results concerning the role of carpooling combined with walking, both being assisted by a powerful mobility application.