This paper studies the eco-driving problem on curved roads using optimal control. The problem is formulated as an optimization one with the aim of maximizing fuel economy. Based on the road map information and dynamic programming algorithm, the vehicle's optimal speed profile for the entire curve is calculated. The impact of road, vehicle and algorithm parameters that have an important effect on fuel use calculation is considered and deeply analyzed compared with previous studies. In addition, the cruise control functionality is also analyzed in this work. Furthermore, co-simulation of Matlab/Simulink and CarSim is conducted for a given scenario and the results show that approximately 3.93% of fuel savings can be achieved compared with a typical driver model.