The complexity of specification development and verification of large systems has to be mastered. In this paper a specification of a real case study, a platoon of Cristal vehicles is developed using the combination, named CSP||B, of two well-known formal methods. This large -- both distributed and embedded -- system typically corresponds to a multi-level composition of components that have to cooperate. We show how to develop and verify the specification and check some properties in a compositional way. We make use of previous theoretical results on CSP||B to validate this complex multi-agent system.