Energy and mobility systems are transitioning, but these changes often focus on low-carbon alternatives without addressing deeper systemic transformations for just, sustainable futures. Predominant systems persist due to perceived limitations of alternatives in acceptability, usability, sustainability, and the complexity of transitions. Transformative change requires shifting value structures and prioritising equality, justice, and collective well-being. However, reconciling divergent visions, addressing fears of disruption, and scaling actionable solutions remain significant challenges. Building on an existing multi-political framework, we analyse five citizen panels that engaged 150 citizens in deliberating just low-carbon transitions in the energy and mobility sectors in five locations across Europe. While citizen panels can incorporate elements of prefigurative politics, they are also closely linked with institutional politics. The transdisciplinary approach highlights inequalities and envisions pathways for energy efficiency in Austria, phasing out fossil fuel vehicles in Brussels, ending peat use in Finland, phasing out coal in Poland, and expanding renewable energy in rural Spain. These cases are characterised by contestation, protests, and local rejection of low-carbon policies. By examining the interplay of contentious, institutional, and prefigurative politics, we explore how these dynamics enable or constrain transformative change, focusing on shared visions, mutual understanding, representation, actions, and navigating institutional power dynamics.