The electrification of transportation is currently seen as one of the key strategies in the sustainable energy transition. This work aims to identify the role of the electrification of transportation from a perspective of the mid-to-long term. The main focus is on the coupling of the deployment of electric vehicles (EV) and power system decarbonization. The paper combines a detailed bottom-up model for the road transportation sector, which features a detailed classification of vehicle types, with the EnergyPLAN tool, a cross-sector and cross-region energy system model of future scenarios consisting of different planning strategies and vehicle charging modes. A case study of the Beijing-Tianjin-Hebei region shows that without increasing renewable power capacity, a 100 % EV penetration can create energy savings and reduce carbon dioxide emissions by a minimum of 11 % in 2050. Moreover, considering the foreseeable technological progress in the battery, a 25 % reduction in the EV initial investment is feasible in all the investigated future scenarios.