Software is the new leading factor for innovation in the automotive industry. With the increase of software in road vehicles new business models, such as after-sale updates (i.e., Function-on-Demand) and Over-the-Air-Updates come into focus of manufacturers. When updating a road vehicle in the field, it is required to ensure functional safety. An update shall not influence existing functionality and break its safety. Hence, it must be compatible with the existing software. The compatibility of an update is ensured by testing. However, testing all variants of a highly configurable system, such as a modern car's software, is infeasible, due to the combinatorial explosion. To address this problem, in this paper, we propose a riskbased change-impact analysis to identify system variants relevant for retesting after an update. We combine existing concepts from product sampling, risk-based testing, and configuration prioritization and apply them to automotive architectures. For validating our concept, we use the Body Comfort System case study from the automotive industry. Our evaluation reveals that the concept backed by tool support may reduce testing effort by identifying and prioritizing incompatible variants wrt to a system update. CCS CONCEPTS • Software and its engineering → Software testing and debugging.