Assuming its the carribean orange GP you have?
Because the paint system is two part, base colour and clear coat, nothing you use will bring back the paint to its former glory.
Its the pigments (most lilely the red part) in the paint which fade under UV light. Because this is protected by the top clear coat layer nothing you will do will restore the colour (Trust me, I was a development chemist at a paint manufacturer
). Orange and reds are notoriously prone to fading, as UV light wavelengths affect these colour horrendously.
What should have happened is to use a wax which contains UV filters, like the ones in sun creams, to protect the paint layer from UV exposure.
My orange GP is faded in places, particularly the rear end. This is probably because the previous owner left the rear exposed to the sun more than the rest of the car.
Certainly a good quality wax will help improve shine, and therefore lessen the impact of faded areas by improving optical clarity. I use meguires on my car, and when it is nice and shiney you dont notice the faded rear end as much.
If it gets too bad you could always consider getting a vinyl wrap done, matt black would look awersome on a GP.
