This paper presents a high-order graph-based model for an electric vehicle (EV) and decomposes the model into a hierarchy suitable for use in hierarchical control. The increased electrification of vehicular systems generates electrothermal performance challenges, and hierarchical control is a strong candidate to mitigate these issues. In order to implement hierarchical control, a multi-level hierarchy of electro-thermal models is necessary. Numerous studies provide electro-thermal models, but this literature is decoupled from the results on hierarchy development through graph clustering techniques. This paper couples these bodies of literature by providing three contributions. First, previous graph-based modeling techniques are extended to include high-order models of electrical components. Second, these techniques are applied to an EV system to produce an EV graph-based model. Third, a graph clustering algorithm is applied to the vehicle model to generate a hierarchy of models. By defining an energy-based clustering metric, the vertices within each level of the hierarchy are partitioned to avoid breaking important power flow connections. This yields a hierarchy of models that can facilitate hierarchical control algorithm development and improve performance of electrified systems.