The demand for more features in a vehicle is growing at an extraordinary rate. This trend especially with emerging autonomous functions shows no sign of slowing. The energy requires to supply this ever growing system goes through multiple conversion, protection and other elements before it actually powers the loads. Considering the loss of each of these elements for a vehicle and multiplying the value by the total numbers of cars, underlines the need for an optimized electrical distribution system to power all loads efficiently.In this paper, Smart Step-Down Convertor is introduced as a power supply to power devices which operate at voltages below the power net voltage while protecting the power net and the devices against faults. In the proposed architecture, each Smart Step-Down Converter is connected to the battery or the power source with the nominal voltage (e.g. 48V) and it provides a programmable output voltage that can be set to the rated voltage of the electric load coupled to it. The rated voltage of electric loads can be equal or lower than the nominal voltage. The proposed system with Smart Step-Down Converters has several advantages compared to its 48V architecture counterparts. First, the 12V battery and 12V power distribution box(s) are eliminated, resulting in not only material savings but also solving some packaging challenges. Second, Smart Step-Down converters enable downsizing the wire harnesses and amount of copper used in a vehicle. Third, energy conversion is more efficient compared to the centralized topology, since each Step-Down Converter is designed to operate at its maximum efficient point unlike the high power convertor, employed in a centralized topology, which operate in a wide power range depending on an amount of the current it delivers. Fourth and the most important advantage is that Smart Step-Down Converters provide a great deal of flexibility for future upgrade. Any loads can easily be upgraded with the similar loads with a different operating voltage by just changing the associated Smart Step-Down Converter. This enables the electrical systems to take advantages of technology in future for example when a more efficient load with similar functions like its current counterpart is available but it requires non-standard voltage.