Differentiated tolling at various time periods neglects issues related to traffic efficiency and operational safety, resulting in no fundamental improvement in the utilization efficiency of road resources. To address this gap, a dynamic pricing model for expressway toll rates (DPM-ET) was proposed within the context of connected transportation. Operational safety was characterized by the standard deviation of vehicle speed, while traffic efficiency was reflected through vehicle speed along with vehicle platoon dynamics. Single-factor pricing models were constructed separately, then integrated with pricing to develop a multi-factor dynamic toll rate model. To enhance expressway resource utilization efficiency, Stackelberg price game theory was used to encourage optimized driving behavior, maintain stable and uniform speeds, and improve traffic flow safety. Simulation results show that compared to the benchmark scheme, DPM-ET improves the average lane speed by 2.01%-6.74% and speed stability by 5.22%, and achieves a maximum platooning rate of 0.9. Compared to similar pricing schemes, DPM-ET improves the value of optimal speed difference (VoOSD) by 4.68-5.37 times, speed stability by 21.17%, and the average lane speed by 5.22%-11.05%. DPM-ET achieves its optimal applicability when the platoon mileage weight is 0.7, the platoon size coefficient is 0.6, the reward coefficient is 0.8, the exponential decay rate coefficient is 0.67, and the maximum standard deviation pricing factor is 3.2.