Blue Beacon using modified pressure washers. It's not a true drive thru like you'd use with your car. You pull into their bay and the top is washed off with spinners. The rest of your coach is cleaned by usually 6 guys with pressure wands. Very efficient and they know which settings to use with the pressure washers. Cost is reasonable - $45-60. Options are to hand dry the coach and tire dressing. Tip is extra....I use them at least twice a year depending on the filth on the coach. Money well spent. Takes me two days to wash it by hand and it doesn't look any better.....Dennis