he emerging vehicular ad-hoc networks (VANETs) have paved the way to Cooperative Adaptive Cruise Control (CACC) applications. With such application, cars can travel in platoons with very small headways and thus achieve considerable capacity and fuel consumption gains. In order to ensure safety while exploiting such gains, intra/inter-platoon communications have to rely on a fast and reliable information exchange. Thus, it is important to define relaying schemes which can ensure that reliable platoon applications can be run over the unreliable wireless channel. In this paper, we propose a new dissemination algorithm for the Decentralized Environmental Notification Message (DENMs) over platoons. Our dissemination algorithm is responsible for electing the vehicles among platoon members for relaying the DENMs. The reliability is met by a proper selection of the best relay based on bidirectional link …