Vehicular ad-hoc networks (VANETs) are one of the recent interests in research industry that have advances in wireless communication and networking models. The ultimate goal of the VANETS is to enable the authorized messaging services towards the vehicles and public networks. To reduce the complexity of the service authorization, it uses proxy vehicles to reduce the complex computational problems. During the authentication of proxy vehicles, it sends multiple messages to frequently get response from the road side units in a more effective way. In the proposed system, proxy based unique authentication scheme is discussed where it cannot provide message authenticity and also it will not resist the mediate attacks. Sometimes, the system accepts the false signatures. Secondly, we proposed a unique identity-based authentication scheme using latest proxy vehicles (ID-MAP). To reconfirm the authentication assurance, the signature is adaptively verified against the chosen message. A robust authentication model is evaluated using the Elliptic Curve discrete Logarithm problem represented as (ECDLP) in the system oracle model.