I use WD-40 Motorbike Silicone Shine as we had a good experience with it in Italy for the 01 R1150GS that it's a tad older and faded in places due to the scorcio weather!
You really have to park it in the shade in summer even if it means you could get the seat covered in bird poo haha
The fading is down to UV causing non-reversable changes to the structure of the plastic - sprays, polishes etc are temporary bodge - only replacement really works - so replace and them keep your bike in the dark
The fading is down to UV causing non-reversable changes to the structure of the plastic - sprays, polishes etc are temporary bodge - only replacement really works - so replace and them keep your bike in the dark