In a speed control system for an automotive vehicle, a speed-differential calculation circuit calculates an absolute value of a time difference between a predetermined period of time corresponding with a desired speed and an instant period of time corresponding with an actual vehicle speed, an acceleration calculation circuit calculates an absolute value of a time difference between the respective instant periods of time, a correction signal generator calculates a sum of the absolute values when each sign of the calculated time differences is positive or negative and calculates a difference between the absolute values when respective signs of the calculated time differences are opposite to each other, the correction signal generator selectively producing correction signals respectively representing the calculated sum and the calculated difference and ceasing the correction signals when each of the calculated values is zero, and a distribution circuit produces a control signal therefrom in response to the respective correction signals, the control signal being applied to an actuator to control an angular position of the engine throttle.