This white paper of the prostep ivip project group SmartSE – Smart Systems Engineering presents practical methodological approaches for determining and evaluating the simulation credibility of numerical simulations to be performed in the context of cross-company, model- and simulation-based development, as already used today in the automotive industry. These so-called “simulation credibility assessments” should be understood as an adaptable solution component on the way to a comprehensive simulation credibility standard or recommendation. The proposed “M&S Credibility Levels” serve as a central element, providing a comprehensible, qualitative evaluation criterion and a link between product managers and decision-makers on the one hand and simulation engineers on the other. This white paper expands the presented methodological approaches for determining and assessing the necessary credibility of numerical simulations with industrial application examples from the automotive industry.