A propulsion device for vehicles includes a device for the partial oxidation of fuel, a fuel tank and a diesel internal combustion engine. The device for the partial oxidation of fuel is in fluid connection with the fuel tank and the diesel internal combustion engine, with the result that at least some of the fuel carried in the vehicle is taken for partial oxidation before combustion in the diesel internal combustion engine. A method for operating such propulsion devices using partially oxidized fuel in the propulsion devices reduces soot emissions.