After driving my G for about 6 month.... My front wheels have darker color than my rear ones somehow.. I am guessing because of brake dust.. I tried to clean with simple green and soap still it is darker than my rear silver ones..
Oh btw i have 18's OEM.. Is there anyway that I can make my wheels look new and shinny silver like when i bought my G ??

 

Use Castrol Super Clean and a PowerWash or CarWash wand.

 

and once you've gotten your wheels back to looking new and shiny, make sure you wax your wheels so that it will make future brake/dirt removal much easier and protect that clearcoat. i use crystal guard on mine. good luck!