Fog-aided computing is an emerging computing paradigm developed for providing various computation services to end users in vehicular fog computing. However, fog vehicles may be untrusted, and results from malicious operations may cause serious accidents. Therefore, we propose a secure and efficient outsourcing computing scheme in vehicular fog computing (SE-VFC), which performs outsourcing computing through fog vehicles with computing resources, and combines lightweight Boneh-Lynn-Shacham (BLS) signature and group signature to achieve batch anonymous authentication of fog vehicles while protecting their privacy in multiple outsourcing tasks. We also verify the correctness of the outsourcing computing results. Security analysis shows that our scheme can authenticate the fog vehicles in the outsourcing computation and preserve their privacy, it can also trace the malicious ones if necessary. Compared with the existing schemes, our scheme has relatively low communication and computation overhead, thus it is quite efficient for batch authentication especially in multiple computing tasks. Extensive simulation results verify the effectiveness and practicality of our proposed scheme in vehicular fog computing.