To reduce emissions, the incentive to commercialize electric vehicles has been encouraged in several countries of the world. With this growth, several challenges arise regarding the new form of vehicular propulsion and one of the main challenges is related to the autonomy of electric vehicles. In this sense, the development of DC/DC converters with the high power density and, mainly, high efficiency have been the object of study by automakers and researchers around the world. The objective of this work is to evaluate the impact of the efficiency of commercial auxiliary power modules in electric vehicles concerning their autonomy and to make a comparison between high levels of efficiency and high power density, important for vehicular applications.