I just bought a brand new Lexus RX300 for my wife. I picked it up a week ago, and they had prepped it and kept it indoors, the paint was absolutely perfect, felt like they had applied something, but no swirl marks whatsoever.
My wife wanted it to stay in the garage and she'd use her old car for a bit. My objective was to do zaino asap, but temperatures were not coopperating. Last Sunday I was able to. The car had been rained on once, and still had less than 100 miles on it. The surface looked perfect, so I did a dawn wash, z-1, and z-2. Afterwards I drove it back into the garage. It looked so great I ran my hand, really just my finger tips over the surface to feel that great smooth feel. I felt and heard scratchiness!!!! But remember it looked absolutely perfect. I did some z-6, but that did not improve it. Then I did the zaino claybar and it was only then perfectly smooth to the touch.
I was called by Lexus today that our new license plates had arrived and I could come by and have them installed. (I went by and picked them up- sorta lame to have them installed) While I was them I asked one of the service mangers if they use any particular products to prep the new cars. He said they use a teflon product from zip that is not available to consumers and that it was very durable, and generally good for six months. So my assumption is that the car looked fine to them, they used this so called teflon product, and when I did my first dawn wash, this product sort of protected whatever tiny specs were on the paint and the clay was the only way to get the paint truly clean.