Background: The Scaled Agile Framework®(SAFe) has been adopted by many automotive Original Equipment Manufacturers (OEMs) for scaling their agile practices. It is one of the ways to improve and accelerate their in-house software development life cycle. Most OEMs have tailored the agile framework to fit their own needs. However, with the increasing complexity of vehicles, especially in terms of embedded software and hardware development, agile release trains (ARTs) face challenges in managing requirements throughout the vehicle development life cycle. Multiple teams working on requirements, consistency of requirements, collaboration, prioritization of requirements between teams, and changing requirements are some of the challenges faced by the SAFe practicing organizations. Objectives: This thesis examines how the requirements engineering within SAFe has been practiced inone of the automotive OEMs, and the challenges its agile release trains face. It addresses the real problems of practical interest and real-life context by interacting with the teams who have been closely working with the requirements daily. It also accumulates the impacts due to the identified challenges. Methods: This study utilizes a case study methodology, which is flexible in design, exploratory, andqualitative. This choice of research method is influenced by the scope of the study, research questions, and the degree of interaction required between us and the participants to collect the data. By conducting semi-structured interviews, a large quality of data isproduced by having a higher level of interaction with participants. The collected data is then probed for newer and unexpected responses using a thematic approach, which helps to identify patterns and themes using large and complex data. Results: This thesis summarizes the requirement engineering practices and challenges faced by theagile release trains in SAFe practicing automotive industry. We approached the agile teams directly and collected the organizational and stakeholder behavior while working with therequirements and the challenges faced. Using intrinsic data analysis, the gathered interview data is understood, and the implications are listed. This study reemphasizes that agile release trains were facing many challenges, especially in the requirements engineeringarea even though the Scaled Agile Framework is practiced. Knowledge gaps, incompleteand misunderstood customer requirements, ineffective communication, fragmented tooling, inadequate management support, and inconsistent requirement engineering practiceare some of the challenges highlighted by the agile release trains.