Jelloslug, did you get your Ultrafabrics samples in yet? As for Electroman's question on cleaning cloth fabric seats, don't you clean them just like you would upholstered furniture?
I was actually kind of shocked to read the article at the beginning of this thread about Tesla dropping leather. I personally like leather in my car. And I love our soft black perforated seats in our MS. We drove in high 90-100 degree weather recently on a trip and with the vented seats on didn't feel the seats sticking at all to my back or legs. Find it hard to believe your bare skin in shorts wouldn't stick to the this faux leather non-vented material in hot and/or humid weather. I see that the Ultrafabrics material is certified for low chemical emissions (probably just like low-VOC wall paint), but for someone who is sensitive to chemicals I still prefer to go the leather route; and yes, I know they use dyes and such in the leather production too. However I've never had a reaction to leather material, whereas I have detected irritating chemicals in faux material. I bought a faux leather case for my iPad that I actually like a lot and has a great feel and has held up really well but it did still have some offgasing for several months that I could detect. Guessing it's a similar material to the material that Tesla is using. In any event still prefer the leather option and not something made of chemicals.