Abstract: A fuel saving device comprising a chamber formed within a housing adapted to be mounted between the carburetor and the intake manifold of an internal combustion engine, the chamber having an inlet end opening which registers with the discharge passage of the carburetor and receives a fuel-air mixture formed in the carburetor, and an outlet end opening which connects to the intake manifold. Micro-porous filter plates are mounted in the chamber transversely to the path of flow of the fuel-air mixture, are spaced from each other in the direction of flow, and a bypass passage is associated with some of the filter plates. Increased vaporization of the fuel results from the flow of the fuel-air mixture around and through the filter plates with the result that the fuel quantity can be reduced, fuel economy improved, and exhaust emissions decreased.