In the twenty-first century, rapid advances are being made in the electric propulsion of vehicles as a countermeasure of global warming. In addition, CO2 emissions from all vehicles are to be stringently regulated to 95 g/km by 2020. Thus, most automakers around the world have had to develop not only hybrid electric vehicles, but also conventional internal combustion engine with energy-saving technology. Battery technology (Li-ion) and semiconductor technology (SiC and GaN) for automotive power supply systems have proceeded to the mass-production stage. In 2011, Verband der Automobilindustrie (German OEMs and suppliers) announced the adoption of DC 48 V for the market of 2020. In this paper, we analyze the needs and impact of DC 48 V and compare it with DC 42 V (current technology). We also try to portray the future view under DC 60 V for automotive power supply systems.