Future cooperative transportation systems will be highly dependent on correct situation awareness that can be established with the help of inter-vehicular communication. Location information from surrounding vehicles will most likely be used in such systems to make automated driving decisions, making it essential to guarantee location assurance. In this paper we propose Vouch+, which provides a scheme to improve trustworthiness of shared location information. The proposed scheme uses cryptographic primitives and mobility awareness to enable location proofs that work also in high-speed scenarios. Vouch+ takes a decentralized approach to establish trust in location information, but can also be used with future 5G infrastructure. The evaluation of Vouch+ using a synthetic dataset from the city of Cologne shows that using a decentralized approach is viable for cases where traffic is dense enough. In addition, simulation-based experiments show that Vouch+ is able to handle the high-mobility environment of vehicular networks and can counteract studied position-based attacks using reaction strategies.