We propose a certificateless aggregate signature (CLAS) scheme for privacy protection based on the certificateless public key cryptosystem and aggregate signature aiming at the common problems of communication security and efficiency in vehicular ad hoc network (VANET). The scheme can resist two different types of adversary attacks under the random oracle model and satisfy the unforgeability of communication messages as well as traceability and anonymity of vehicles. The scheme avoids the key escrow problem and certificate management. Based on the bilinear pairing operations, the aggregation verification of multiple messages is realized through aggregation signature. We quantitatively analyze the computational overhead of the scheme and define a new variable of computational efficiency. Our scheme is proved to be more efficient when V2I communication is carried out in urban roads compared with other schemes.