A control system operative to establish a coordinated mixture of gaseous and distillate fuels for a high capacity off-road vehicle equipped with a diesel-electric drive including a propel mode includes an electronic control unit and a gaseous control unit. The electronic control unit generates an auxiliary control signal which is determinative of a steadily increasing quantity of gaseous fuel to be included in an operative fuel mixture. Upon indication that one or more predetermined operating parameters have exceeded a threshold level, the electronic control unit generates auxiliary control signal which decreases the quantity of gaseous fuel and maintain the quantity of gaseous fuel to be included in the operative fuel mixture once the predetermined operating parameters return below the threshold level.