•Energy consumption is nearly 8 times lower for electric vehicles.•Electric vehicle can be currently feasible in Brazil for reducing CO2 emissions.•CO2 emissions from electric vehicles can be 10–12 times lower.•Substitution of 25% of a taxi fleet by electric vehicles reduce 1000 tons CO2/year.•Substitution of total taxi fleet by electric vehicles reduce 5600 tons CO2/year. This paper evaluates the impacts on energy consumption and carbon dioxide (CO2) emissions from the introduction of electric vehicles into a smart grid, as a case study. The AVL Cruise software was used to simulate two vehicles, one electric and the other engine-powered, both operating under the New European Driving Cycle (NEDC), in order to calculate carbon dioxide (CO2) emissions, fuel consumption and energy efficiency. Available carbon dioxide data from electric power generation in Brazil were used for comparison with the simulated results. In addition, scenarios of gradual introduction of electric vehicles in a taxi fleet operating with a smart grid system in Sete Lagoas city, MG, Brazil, were made to evaluate their impacts. The results demonstrate that CO2 emissions from the electric vehicle fleet can be from 10 to 26 times lower than that of the engine-powered vehicle fleet. In addition, the scenarios indicate that even with high factors of CO2 emissions from energy generation, significant reductions of annual emissions are obtained with the introduction of electric vehicles in the fleet.