This work focuses on comparing the ecological potential of variable speed limits (VSLs) and signalized access control. A synthetic two-region network composed of an urban and a peri-urban area is considered. This study aims at improving the energy efficiency in both areas. A microscopic traffic simulator (SUMO) is used to model the dynamics of the system. It is controlled by a nonlinear model predictive control (NMPC) framework based on a macroscopic traffic model, which is an adapted version of the cell transmission model (CTM). The controller is coupled with an artificial neural network (ANN) to predict the fuel consumption. Finally, microscopic physical energy and NOx models are used to evaluate the performance of both control actuators. The results reveal that VSLs are more promising due to the smoother variation of the densities.