A vehicle control method in a hybrid electric vehicle including an internal combustion engine, a battery, an electric motor, and a control unit. The method includes estimating an estimated vehicle velocity trajectory, estimating an initial engine power trajectory, simulating state of charge of the battery with the vehicle velocity trajectory and the initial engine power trajectory, estimating an initial terminal co-state value, simulating backward co-state dynamics using the state of charge and vehicle velocity trajectory, to obtain a resulting co-state trajectory. The co-state trajectory is used to solve a minimization control and propagate state of charge dynamics forward in time. The method includes updating control and the co-state trajectory, adjusting the terminal co-state value, and controlling a usage of the battery and the internal combustion engine. The method can be performed to optimize the engine power trajectory to minimize fuel consumption in real time.