This paper addresses the problem of the joint design of the mobile communication system and the control scheme for enabling vehicle platooning applications. Vehicles communicate essential information for platooning control through multi-hop vehicle-to-vehicle (V2V) communications and are assisted in this task by Road Side Units (RSU), when available. While classical approaches, adopted in previous and current mobile systems, consider the application needs solely as requirements for the communication network, we advocate a bi-directional interaction of application and communication network. We first study the impact of different communication strategies on the application-level performance, namely the inter-vehicle distance in the platoon. Such schemes introduce a tradeoff between the packet delivery rate and the additional delay introduced by relaying. In order to assess the impact of both metrics, we start by developing a Markov model for the different communication links (inter-vehicle and vehicleto-RSU). We then propose a cross-layer approach that adapts the application layer (platoon control parameters) to the observed Medium Access Control (MAC) layer performance. We demonstrate via simulations the benefit of the proposed relaying scheme, and that a joint design of application and communication systems is essential for enabling the integration of industrial applications in future generation networks.