This work studies the impact of drive cycles on the power semiconductor temperature, and consequently on the reliability figures. The paper quantifies the reliability errors stemming from the use of standard mission profiles by comparing them to data sets using real-life high-resolution mission profiles. It is found that standard drive cycles underestimate the stress on the power semiconductors. The paper thus proposes a new and more realistic Drive Cycle for Reliability Assessment (DCRA) to be used for lifetime estimation of power electronic components.