With the prevalence and development of GNSS technologies, location-based vehicle services (LBVS) have experienced a rapid growth in recent years. However, location is a sensitive and private piece of information, so the design and development of such services just take the clients' privacy concerns into account. In this paper, we propose a new electronic toll pricing system based on group signatures, which provides a strong guarantee for the clients' anonymity within groups. Our system achieves a balance between privacy and the communication overhead imposed upon the users.