The amount of electronics in vehicles is growing quickly, thus systems are becoming increasingly complex which makes the engineering of these software intensive systems more and more difficult. In the automotive industry the use of product line architectures enables a set of vehicles to share architecture to decrease cost and increase quality. In this study we investigate key issues related to realworld decisions regarding electrical and electronic product line architecture for heavy vehicles. To extract key issues a multiple exploratory case study at two heavy vehicle manufacturers was performed. We used semi-formal interviews complemented with a survey to validate the results. The contribution of this study is 14 issues that reflect the situation at the two companies. Many of the identified issues relate to non technical areas such as organization, process, methods and tools, and management. Moreover, possible actions to deal with these issues are discussed.