<p>This study conducts a mixed qualitative quantitative survey of security mechanisms for the Internet of Vehicles (IoV), combining traditional cryptographic and blockchain based approaches. By analyzing 63 blockchain based IoV security frameworks published between 2019 and 2025, the paper provides a comprehensive comparison of authentication, privacy, trust management, and access control mechanisms. Unlike prior surveys limited to purely descriptive analysis, this work offers a normalized quantitative comparison and performance oriented synthesis based on commonly reported metrics such as latency, communication overhead, computational cost, and energy consumption. To account for heterogeneous evaluation environments across studies, reported results are mapped into standardized relative performance categories, enabling objective cross study comparison and identification of key trade offs. The findings highlight the need for hybrid, scalable, and energy efficient blockchain based IoV security frameworks that integrate decentralization with adaptive intelligence, providing a roadmap for future secure and intelligent vehicular networks.</p>