Hi Bob,
You'll want to steer WAY clear of the brushes at those coin operated car washes. That is, if you care at all about the finish on your car. If you think about it, or have noticed anyone using those brushes, you'll know that they're consistently being used on Jeeps and other trucks that just got finished with a weekend in the mud. Now, all that mud and dirt is trapped in that brush, along with pebbles and all sorts of other junk you don't want drug across your paint. Not to mention, the bristles on those brushes aren't exactly the most delicate, either. At most, use the coin-op to spray your car off if you're not after a showroom finish. Just know that the soaps in those machines are fairly strong; strong enough to strip the wax and some sealants off your paint. Look into using the 2 bucket method with a grit guard if you're wanting the best for your car.