One of the main problems in autonomous electric vehicles is the volume of the electrical systems, because bulky components carry additional mass and high cost to the total system. Consequently, Interleaving phases and magnetic coupling techniques have been reported as effective methods for increasing the power density of the DC-DC converters that interface the storage unit with the electric motor. However, there are several converter topologies that use these techniques. Therefore, a volume assessment of these topologies is required in order to have a complete understanding when an electric power train is designed. In this paper, a volume modeling methodology is introduced with the purpose of comparing four different DC-DC converter topologies: Single-Phase Boost, Two-Phase Interleaved with non-coupled inductor, Loosely Coupled Inductor (LCI) and Integrated Winding Coupled Inductor (IWCI). This analysis considers the volume of magnetic components, power devices (conventional and next-generation), cooling devices and capacitors. As a result, interleaving phases and magnetic coupling techniques were validated as effective to downsize power converters. In particular, it was found that LCI and IWCI converters offer lower volume in comparison with other topologies.