The next-generation electricity grid (“smart grid”) is expected to integrate interoperable technologies – particularly in the energy, transport, information and communication fields – with the aim to increase reliability, affordability and sustainability considering at the same time, distribution systems and market operation. In order to gauge the implications of the anticipated paradigm shift for the electricity system, new reference architectures and assessment methodologies shall be developed to properly capture the interactions between the different actors (especially utilities, operators, energy aggregators, end-users, etc.) and technologies to value and allocate the costs and benefits of such transformation. Against this background, this paper proposes a conceptual architecture and an assessment framework to explore how high penetration scenarios of electric vehicles and intermittent renewable generation can complement each other in emerging distribution networks. We start from the identification of the smart grid functionalities to be implemented in a system with distributed power injections under the need to supervise and coordinate myriads of decentralized and interoperable energy sources and actors. Relying upon the proposed smart grid conceptual architecture, we develop an assessment framework to maximize the renewable electricity and electric vehicle penetration for given electricity and transport systems. The application of the proposed assessment framework to a realistic case study, representing the distribution and mobility systems of a typical mid-size Italian city, illustrates how some of the limitations and constraints of the current electricity network operation and design approaches can be addressed and overcome. We show how integration of substantial amounts of energy production and electric-based transport technologies can be achieved while improving the reliability and sustainability performances of the emerging power systems.