Yeah, I second the use of foam canons. I have a Chemical Guys (CG) one and it's ok with my power washer but could be better (might actually be my pressure washer
). Also use the CGs two bucket method with grit screens in the bottom when washing your car.
I have yet to pick my Stinger up and I have already told the dealer I don't want the car groomed.
Dealer groomers are trained to be quick not fussy. My brother is one and he told me how they operate.
If you let the dealers service dept groom your car you will end up with swirls and lines in the paint over time.