This paper presents an in-depth view of how architects work with maintaining product line architectures at two internationally well-known automotive companies. The case study shows several interesting results: The process of managing architectural changes as well as the information the architects maintain and update is surprisingly similar between the two companies, despite that one has a strong line organization and the other a strong project organization. The architecting process found does not differ from what can be seen in other business domains. What does differ is that the architects studied see themselves interacting much more with other stakeholders than architects in general. The actual architectures are based on similar technology, e.g. CAN, but network topology, S/W deployment and interfaces are totally different. The results indicate how the company’s different core values influence the architects when defining and maintaining the architectures over time. One company maintains four similar architectures in parallel, each at a different stage in respective life-cycle, while the other has a single architecture for all products since 2002. The organizational belonging of the architects in the former company has been turbulent in contrast to the latter and there is some speculation if this is correlated.