The exhaust gas from an internal combustion engine is fed to a high speed turbine, serving to rotate the turbine and effecting a first separation stage by stratifying of heavier and lighter exhaust gas components which exit from the turbine in opposite directions, the heavier components having a second stratifying separation in a vortex tube to separate combustible pollutants from non-combustible components. The lighter pollutants effected in the first separation and the combustible components effected in the second separation which are also pollutants are then brought together to be mixed in a chamber and ultimately fed back to the engine carburetor. However, the so-called clean exhaust gases, namely carbon dioxide and water vapor pass out of the vortex tube to atmosphere by way of the vehicle exhaust. The mixing chamber can also function, if need be as a reservoir to collect condensate under abnormal conditions for release via a petcock. At the outlet end of the vortex tube, i.e., the exhaust end of the system, a chamber is provided for the second separation stage to collect the pollutants and, if need be, under abnormal conditions trap liquid condensate for ultimate release via a petcock. Inasmuch as the stratifying turbine in the first separation stage revolves at an extremely high speeds, a novel water cooled bearing mount is provided wherein water is tapped from the vehicle radiator and returned thereto for cooling the bearing. In addition, an air blower may be provided for furnishing air to be entrained with the mixed pollutants passing back to the vehicle carburetor. Such air blower is readily operated by a belt from the fan and water pump belting and pulley arrangement of an automobile. The system is entirely mechanical in operation and cannot in any way be harmed by the type of fuel used in the vehicle, for example leaded or non-leaded. Further, there may be provided in the system an exhaust gas mixing chamber for the components described above having a water charge therein through which the components to be mixed bubble in the presence of zinc rods or other zinc surfaces acting as a catalyst. The arrangement effects formation of formaldehyde and nitrous acid in the water charge which can be drained out periodically. This prevents aldlehyde gases from passing to the engine which can have the effect of retarding combustion, and which might readily be formed in a mixing chamber made of, e.g., aluminum. Also, prevention of solid aldehyde compounds precludes formation of gummy substances which could cause valving in the system to stick.