I've reviewed a few car washes around the metro Charlotte area, and been unimpressed by the majority of them. I tried Sam's Xpress about a week after their opening in November 2012. The concept is nice - keep costs low by providing complimentary self-service interior cleaning facilities.
Unfortunately, Sam's invested in fairly low end car washing technology. The rotating brushes just don't get the job done. Admittedly, I have very high standards for car washing - I detail my vehicles personally in warmer weather. Nevertheless, Sam's inferior brush system left a great deal of dirt on my vehicle. This same dirt was easily cleaned the following week when I visited a better wash facility with higher end equipment, Quick C's in Rock Hill.
I'd also like to add that the local community did not welcome Sam's. The owner of Sam's elected to build a structure that failed to blend in with the aesthetics of the area, opting for insanely bright primary exterior colors like a crayola crayon box. I would have been a regular at this wash had they invested in better equipment, and had worked a little harder to blend in with the area.