A bar code symbol reading system is disclosed comprising a hand-supportable bar code symbol reading device which embodies an electronically-controlled bar code symbol reading engine for producing a raster-type laser scanning pattern in either a hands-free or hands-on mode of operation for scanning 1-D and 2D bar code symbols. The viewed image signal is communicated to a central processor. The control system makes an assessment of the fuel saving control by learning fuel consumption within a predetermined learning zone, and inhibits the fuel saving control or executes another control in the learning zone next time the vehicle travels through the learning zone, if the assessment shows a fact that the fuel saving control executed in the learning zone did not effective to save fuel.