This paper presents a high-reliability Grouping-Based communications trust model in Vehicular Ad-hoc Networks (VANET). The proposed solution consists of two distinct components: First, the Dynamic Group Head Selection (DGHS) scheme to improve the Group Head’s (GH) stability by considering the reliability of the communication link with the Road Side Unit (RSU). Second, a hybrid Dynamic Trust Model (DTM) scheme improves trustworthiness by considering the node’s dynamic conditions and records. Average GH Lifetime and Average Query Success Rate were used as metrics to evaluate the performance of the grouping algorithms to those of Cluster-Based Location Service (CBLS) and Trust-based Security for Message Exchange (TSME). The proposed DTM was compared to TSME and MiTM Attack Resistant Trust Model (MARINE). With a maximum density of 900 vehicles, DTM improves the average GH lifetime by 43% compared to CBLS and 19% compared to TSME. Similarly, DTM increases the query success rate by 10% compared to the CBLS and 23% compared to the TSME, even at the slowest speed (40 km/h). In terms of node density precision, DTM decreases by around 5% for MARINE and 10% for the TSME approach. In conclusion, it has been shown that the proposed schemes are reliable for various position-based VANET applications that need precise positioning and trusted messaging.