Multi-Agent systems (MASs) are used in more and more critical domains such as transportation or medical technology, although their use is limited by the lack of validation and adequate software engineering support. Formal methods have proved their strength in that regard. We propose the use of the B formal method as a sound software engineering approach for specifying and validating MASs. We illustrate this approach on the basis of the agent-based platooning problem, i.e. vehicles moving in a convoy. We hereby aim at demonstrating the solid support provided by formal methods to such systems and how their use help the extraction of implicit knowledge from the models for MASs engineers.