A system for reducing the emissions of the oxides of nitrogen(NOx) and improving the fuel efficiency of a diesel engine having at least one combustion chamber and a camshaft and a crankshaft and an intake port and an operator controlled throttle with at least one electronically actuated diesel fuel injector; a diesel fuel supply reservoir communicatively connected with the diesel fuel injector and including diesel fuel pumping means for maintaining diesel fuel pressure at the inlet of the diesel fuel injector; at least one electronically actuated water and/or alcohol injector; a water and/or alcohol supply reservoir communicatively connected with the water and/or alcohol injector and including water and/or alcohol pumping means for maintaining liquid pressure at the inlet of the water and/or alcohol injector; and an electronic regulating means for controlling the rate at which atomized diesel fuel and water and/or alcohol are independently injected respectively into the combustion chamber and intake port. The electronic regulating means is being operatively connected to the injectors and is responsive to one or more of air temperature in the air intake manifold, the position of the throttle, the intake manifold pressure, the camshaft position, the crankshaft position, the engine rotational speed wherein the amount of water and/or alcohol injected into the intake port is controlled as a function of both the amount of diesel fuel and alcohol injected and the ratio of diesel fuel and alcohol to air in the combustion fuel mixture to reduce NOx emissions and improve fuel efficiency over the operating range of the diesel engine.