We are interested in the role of field user interaction data in the development of In-Vehicle Information Systems (IVISs), the potentials practitioners see in analyzing this data, the concerns they share, and how this compares to companies with digital products. We conducted interviews with 14 UX professionals, 8 from automotive and 6 from digital companies, and analyzed the results by emergent thematic coding. Our key findings indicate that implicit feedback through field user interaction data is currently not evident in the automotive UX development process. Most decisions regarding the design of IVISs are made based on personal preferences and the intuitions of stakeholders. However, the interviewees also indicated that user interaction data has the potential to lower the influence of guesswork and assumptions in the UX design process and can help to make the UX development lifecycle more evidence-based and user-centered. CCS CONCEPTS • General and reference → Surveys and overviews; • Human-centered computing → HCI design and evaluation methods; Empirical studies in HCI. KEYWORDS interview study, user experience, in-vehicle information systems ACM Reference Format: