When my car goes in..... there are "No Wash" notes all over the place....
If you do not want swirl marks all over your car, I suggest you do the same.
A dealer "courtesy" car wash is what it is.... judging from the paint of their loaner cars (which probably gets washed there all the time) I would stay away from it.
Retired: 2011 E92 M3 AW w/ Silver Novillo ZCP, ZTP, ZPP, 494, 6FL, 507, 302 & 415.....ED April 29th, 2010
Retired: 2007 E92 335i -Space Gray, Black Leatherette + Alum, Nav, ZCW, ZSP, PDC, CA & Sunshade.....ED Oct 19th, 2006