•The novel Eco-CACC scheme combines both advantages of eco-driving and platooning.•Excellent energy and car-following performance for the CAV platoon.•CAV platoon can pass the continuous signalized intersections without separation.•The favorable improvement of calculation speed using a modified DP algorithm. Vehicle driving patterns greatly impact the sustainability of the transportation system. Based on V2X communication, the ecological cooperative adaptive cruise control (Eco-CACC) is proposed combing the advantages of eco-driving and car-following to minimize the energy consumption of the connected automated vehicles platoon. Herein, the vehicle platoon behavior in the scenario of driving through a signalized intersection exhibits great benefits for sustainability which is even improved along corridors with more traffic lights. In the velocity trajectory planning process, a modified dynamic programming algorithm is formulated with the switching logic gate of two types of optimal control problems to increase the computational speed. By testing in the real-world scenario, the results of the proposed Eco-CACC demonstrate excellent energy performance which improves 8.02% compared to manual driving with the constant acceleration policy. Moreover, energy can be further improved by 2.02% and 1.55% when the car-following strategy is selected with MPC and IDM algorithm.