Yea lots have that option. It's pretty much a useless option though. Causes more headaches than anything. However to answer the question. You pressure wash the crap and crud off soak the car down and then grab a wash mitt filled with your choice of soapy water actually hands wash the car and then rinse would be the proper way to apply and remove soap.
my PW has a tank on it for soap... i use it every time i wash the car... i have quick disconnects on the hose and PW so its a breeze to set up... im also looking into a foam cannon
