<p>Integrated sensing and communications (ISAC) is emerging as a key enabler for vehicular networks, aiming to jointly support high-resolution sensing and ultra-reliable low-latency communications under high mobility. This survey provides a structured overview of ISAC for vehicular networks. Specifically, by comparing this paper with related surveys and introducing the preliminaries of ISAC and vehicular networks, we first demonstrate the necessity and potential of this survey. Subsequently, we review representative techniques for system performance optimization of ISAC-enabled vehicular networks, with emphasis on resource allocation, beam management, and reconfigurable intelligent surfaces (RIS)-based coverage enhancement and robustness. Beyond performance, we consolidate security and privacy considerations of ISAC-enabled vehicular networks, covering physical layer security mechanisms, network-level protection, and privacy-preserving aspects. Finally, we identify key research challenges related to scalability, imperfect modeling and hardware non-idealities, and unified security-privacy-performance design, aiming to support both academic research and practical deployment of ISAC-enabled vehicular systems.</p>