Nowadays novel control technologies in vehicle and engine have been being developed to meet the demand for the improvement of fuel efficiency. Even though alternator generation control strategy is not a newly developed one and widely applied to a passenger car, there is no application to commercial vehicles. In this paper, a novel alternator generation control algorithm considering the driving characteristics of commercial vehicle is suggested. In addition, an actual alternator generation controller is designed and developed to implement suggested algorithm. Especially, by determining the level of control variables with a Robust Design method, not only fuel efficiency but also stability in voltage control against the noise of electric load is improved. With this newly developed logic and controller, fuel efficiency was validated as having 2.2% improvement through actual road test.