Platooning of connected automated vehicles (CAVs) on highways has attracted the interest of researchers, companies and administrations for years. This interest has yielded a vast literature on CAV platooning, which generally describes its benefits in terms of traffic efficiency, safety and environmental impacts, among others. However, the boundary conditions of these studies and the reported magnitude of these benefits vary greatly among the different contributions. In this context, this paper presents the result of a comprehensive literature review on CAV platooning on highways, organizing the existing research and establishing links between the different strategies proposed and their expected impacts. Starting points for future investigations are suggested, and the research gaps to be addressed are identified. The analysis performed shows that the current state-of-the-art has two major limitations. First, few CAV platooning strategies have been proven to be asymptotically stable, which should be a requirement for any feasible solution. Second, in most cases, the CAV platooning algorithms are simplistic adaptations from existing car-following models proposed for human driving that, therefore, unnecessarily transfer current traffic-related problems to future cooperative environments.