This document discusses using rankings to measure transport system performance and impact policy. It proposes developing a "Good Mobility Index" (GMIR) that incorporates transportation volume, greenhouse gas emissions, deaths, and infrastructure costs to measure sustainability. The document suggests rankings may influence policy if scientists agree on methodology, rankings are linked to targets, future visions are presented, society is engaged, and leaders from low-ranking areas are involved in proposing solutions. Regularly discussing rankings and getting the timing right for policy changes could help ensure they have impact.