Power electronics continue to be an area of active research in the field of electric vehicle design. Safe, reliable, and efficient conversion from DC battery power to AC for the electric motors is an essential part of overall vehicle performance. An IGBT is a standard power electronics device that can be used to synthetically manufacture an AC signal from a DC power source. These specialized transistors rapidly change the direction of current flow in a way that approximates a pure AC power supply output and can thus convert battery power to a form that is appropriate for the AC motors used in modern electric vehicles. Early generations of electric vehicles tended to use standard components from third-party suppliers for both the IGBT pack and the cooling module or “cold plate” responsible for maintaining acceptable operating temperatures. These components may have been designed for entirely different applications and were not always optimal for electric vehicles. As the industry matures, the need to tailor designs specifically to the demands and performance of an electric vehicle have motivated both traditional power electronics manufactures, and vehicle manufactures to invest in simulation and testing of bespoke designs for both the IGBT and the cooling modules. Efficient and accurate simulations are essential to bringing high performing designs to market within the tight time frames required by the competitive electric vehicles industry. In the current work, a single IGBT pack serves as the baseline for two different simulation techniques to compare the viability of each to the challenge of power electronics design for electric vehicles. Specifically, we compare a thermal stress analysis where the cold plate is modeled as a constant temperature boundary condition on the bottom of the IGBT to one where the cold plate and coolant flow are included in the simulation. A comparison of the max and average temperatures and stresses in the essential electronics components is made. We also quantify the additional computational resources required to perform the fluid/solid simulation vs the solid alone. The solid simulations consist of a finite-element thermal stress simulation within Siemens Simcenter STAR-CCM+ while the coupled fluid/solid model combines a finite volume CFD model with the same finite element solid-stress model used in the solid-only simulation. The thermal solution for the fluid and solid model are iteratively solved until an energy balance is reached, at which point the thermal stress is calculated. To make the comparison meaningful, the coolant material properties were optimized such that the final average temperature on the IGBT lower plate was 60 °C, which is equal to the constant value specified as the boundary condition in the solid-only simulation. The results demonstrate significant differences in both the peak and average temperatures and stresses within the IGBT components. We also show that while the time required for a coupled simulation is large relative to the solid-only, it remains very attainable for most practitioners of CAE in the relevant industries. This variation in critical simulation outputs suggests that higher fidelity modeling is one way to advance the design of these components, and the computational requirements are within the reach of most of the relevant engineering companies.