Electric vehicles (EVs) and plug-in hybrid electric vehicles (PHEVs), which obtain their fuel from the grid by charging a battery, are set to be introduced into the mass market and expected to contribute to oil consumption reduction. In this research, scenarios for 2020 EVs penetration and charging profiles are studied integrated with different hypotheses of power sources expected in electricity generation for year 2020. Simulations of the impacts in load profiles and spot prices are obtained for the Portuguese case study as well as the emissions balance between the transportation and the electricity generation sectors. Simulations made for year 2020 in a scenario of low hydro production and high costs, estimate that the price could reach the 17 cents/kWh (including wholesale, plus the net access, plus retailer revenue) for a 2 Million EVs charging mainly at peak hours. In an off-peak recharge the price reduces to about 7 cents/kWh. In a high hydro production and low wholesale prices, an off peak recharge could reach 5.6 cents/kWh. Reductions in primary energy consumption, fossil fuels use and CO 2 emissions of 4%, 12% and 9% respectively were verified from the transportation and electricity generation sectors together when compared with a Business as usual (BAU) scenario without EVs and the same electricity production mix. In these extreme cases, EV energy prices were between 0.9€ to 2.8€ per 100 km.