Injection molding method of a part for vehicle interiors, comprising the steps of: - arranging a mold having a first injection chamber shaped so as to define in negative a base of said part, - injecting thermoplastic material, such as polypropylene, into said first injection chamber, - extracting the base from the first injection chamber and placing it in a second injection chamber on the side of a lower wall of said second injection chamber, - inserting a lining film in said second injection chamber and deforming it so as to arrange it, on the side of an outer surface thereof, adhering to an esthetic wall of the second injection chamber opposite the functional wall, - injecting an intermediate layer of plastic material, such as a thermoplastic elastomer, in a gap between an inner wall of the base facing the lining film, and an inner surface of the lining film opposite said outer surface so as to create a single sandwich structure, wherein said intermediate layer is present between the lining film and the base, - the intermediate layer having lower hardness than the base and forming a yielding padding for the lining film; wherein a step is provided to feed the lining film into the second injection chamber through an automatic feeding device and, through a locking and sealing device, peripherally sealing against the mold, on the side of the esthetic wall, a portion of said lining film equal to or greater than the base so as to exceed the second injection chamber, to create a sealed chamber between the lining film and the esthetic wall of the second injection chamber; and wherein a step is provided to associate the locking and sealing device with a heating device so as to heat the lining film during the step of deformation and adhesion of same to the esthetic wall of the second injection chamber. - arranging a mold having a first injection chamber shaped so as to define in negative a base of said part, - injecting thermoplastic material, such as polypropylene, into said first injection chamber, - extracting the base from the first injection chamber and placing it in a second injection chamber on the side of a lower wall of said second injection chamber, - inserting a lining film in said second injection chamber and deforming it so as to arrange it, on the side of an outer surface thereof, adhering to an esthetic wall of the second injection chamber opposite the functional wall, - injecting an intermediate layer of plastic material, such as a thermoplastic elastomer, in a gap between an inner wall of the base facing the lining film, and an inner surface of the lining film opposite said outer surface so as to create a single sandwich structure, wherein said intermediate layer is present between the lining film and the base, - the intermediate layer having lower hardness than the base and forming a yielding padding for the lining film; wherein a step is provided to feed the lining film into the second injection chamber through an automatic feeding device and, through a locking and sealing device, peripherally sealing against the mold, on the side of the esthetic wall, a portion of said lining film equal to or greater than the base so as to exceed the second injection chamber, to create a sealed chamber between the lining film and the esthetic wall of the second injection chamber; and wherein a step is provided to associate the locking and sealing device with a heating device so as to heat the lining film during the step of deformation and adhesion of same to the esthetic wall of the second injection chamber.