The rapid development of the automotive industry brings great convenience to people. However, some problems such as fuel consumption, pollutant emissions, and traffic congestion have become more and more serious. Especially in urban freeway, how to solve these problems attracts the attention of researchers. Therefore, with the concept of “carbon peak and carbon neutrality”, this paper designs an advanced eco-driving assistant system for intelligent connected vehicles based on vehicle-to-everything (V2X) communication system. Firstly, the intelligent roadside equipment collects traffic and vehicle information in the urban freeway. Secondly, the edge computing server fuses the data to form a holographic perception of dynamic traffic flow and transmits regional road traffic safety warning prompts. At the same time, a minimum energy consumption speed guidance model for vehicles is proposed considering the fused data. Thirdly, an application in V2X communication is designed to display the safety warning prompts, the status of the traffic and vehicles, and the optimal speed guidance. Finally, experimental results from field tests show that the energy consumption of vehicles with the advanced eco-driving assistant system is significantly reduced. In addition, the driver can obtain current traffic status and safety warning prompts, which improves driving safety.