Think this through....
Unlikely a dealer will have a touchless car wash; they couldn't put the convertibles through. Plus, I've never seen one which actually does anything more that get the top layer of dirt off, always they seem to leave a layer behind.
Non-touchless car washes... always a bad idea for the usual reasons.
If the dealer *does* do a hand car wash... Two problems... first, do you really think they'll use fresh clean high quality microfiber drying towels on every vehicle, or will they reuse the same drying towels over and over, carrying the grit from the previous car's rocker panels across your hood and roof? Second, will the person doing the washes be a skilled professional detailer who cares about the paint finish... or some minimum wage person who splits his time between sweeping the shop, acting as go-fer, and washing cars?