As self-organizing, highly heterogeneous and multi-interactive networks, vehicular ad-hoc networks (VANETs) are rapidly improving the efficiency of modern traffic. This promising technology is significant for supporting current intelligent transportation by cooperative data sharing and processing. Considering requirements for secure interactions and the limitation of resources in VANETs, protecting data authenticity while enhancing computational efficiency has become the main challenge. A certificateless aggregate signature (CLAS) can not only ensure data security, but also reduce communication costs, which is suitable for a resource-constrained environment. However, most existing CLAS schemes either own serious security vulnerabilities or result in tremendous computational overhead. In this article, we propose an efficient, privacy-preserving, and pairing-free CLAS scheme with enhanced security. We prove that it is existentially unforgeable against adaptive chosen message attacks in the random oracle model. Performance evaluation illustrates that our proposed scheme is more appropriate to the VANETs scenario.