I use a version of Dennis' home made cleaner car. Works as good as anything else I've tried. I run 2, one with a scotchbrite pad and a second with paper towel pad to pick up the crud the front one loosens.
Do a search here for Dennis' car, he will probably email the instructions on construction to you. He has done so in the past.
If you are dead set on a commercial version, I like the look of the R & L Car.
http://www.rllines.com/