Once the factory coating is "gone" usually through UV degradation, there are no "genie in a bottle" products that will restore the factory finish other than a professional repair. (refinish the surface) They will only prolong the inevitable.
The front cap doesn't look that bad in the photo (reflections of the photographer) but the oxidation at the BOTTOM where the sunlight (UV exposure) is lower is puzzling. As Doug mentions, could this be a previous factory warranty repair? There is no vehicle history.
The rear cap clear coat is clearly "gone." Only a professional refinish will fix that.
Chum lee