An engine control system which may be used in automotive vehicles includes first correlation data representing correlations between performance parameters associated with different types of performances of a combustion engine and uncorrelated common factors existing among the performance parameters and second correlation data representing correlations between the common factors and combustion parameters associated with combustion states of fuel in the combustion engine. The engine control system determines target values of the common factors using the first correlation data and also determines target values of the combustion parameters using the second correlation data. The engine control system determines command values as a function of the target values of the combustion parameter and outputs them to actuators which control combustion states of fuel in the engine for achieving desired levels of the performances of the combustion engine. This enables the performance parameters to be controlled independently of each other without any interference.