From all accounts it will hold up to car washes. There is a video of a guy power washing his wheels and grill holding the nozzle 2 inches away without incident! Other users have reported excellent durability over the course of many months.
To clarify - I did NOT use the glossifier pictured above. It came with my kit but after I saw the matte, I decided that I really liked the contrast on my particular car.
I too was considering powder coating but this way, I can go back to stock whenever I want. The added protection to the wheels finish is also a plus.
Thanks for the compliments!