Ill be a buyer of any coat hook / valet system you can come up with. I also think you need a backseat center arm rest/cup holder unit.
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I lay my dry cleaning flat in the back. There is always too much for a hook anyway, and I don't want to block visibility. I hang my coat on the passenger side seat, also not to block visibility. Works fine for me and is the same routine as my former car that did have hooks. There are definitely some things my other car had that the S does not. It didn't take long to adjust.
How are you "hanging" it exactly? I'm less worried about dry cleaning and more concerned about my sportcoats/suit coat if the day.