Due to the massive wireless communications among numerous vehicular and static entities in the internet of vehicle networks, these networks became vulnerable to eavesdropping and interference. Thus, using physical-layer security techniques in vehicular networks can significantly enhance secrecy performance. This paper investigates the secrecy performance of cooperative vehicular relaying networks (CVRNs) over mixed Nakagami-𝑚 and double Nakagami-𝑚 fading channels in the presence of a single eavesdropper and cochannel interference. The relaying node is assumed to operate with different relaying schemes, namely, decode-and-forward, amplify-and-forward with variable gain, and amplify-and-forward with fixed gain. Hence, mathematical expressions for the average secrecy capacity (ASC) are obtained for the relaying schemes. Furthermore, a power allocation model is proposed to maximize the derived ASCs in terms of the source and relay nodes’ transmission powers, enhancing the relaying schemes’ secrecy performance. The results demonstrate the impact of channel condition and the strength of interference on the system secrecy performance. Moreover, the results show that the proposed power allocation model enhances the secrecy performance significantly compared to the equal power distribution model.