The release process is a crucial element in the development of software-intensive systems, as it bridges the gap between the development of a system and its operational use. A short release process enables a fast time to market, but also puts high demands on the efficiency of integration and testing, which typically constitue principal release process steps. This paper reports findings from an exploratory industrial case study focusing on system testing in an automotive electrical system release process. We provide a description of how system testing is performed and integrated in the release process in the automotive domain, and identify a set of challenges observed in the studied setting. The case being studied is Scania, a major Swedish automotive company.