As long as you dont use dish soap, the clear coat will be fine...
Personally, I reccomend the Mr. Clean auto-dry carwash system. I have my own kit, and we use the system at my work to clean our customer cars... one of the best systems I know of, works just like it says it does. And better yet, the delux kit is only like 50$... the basic kit is like 20$ now I think...