I bought the NANO fabric protector from QVC. It's pretty good! on QVC they showed a pair of jeans and poured motor oil on the protected side and it just rolled off so I thought it would be great for the top of my Crossfire.
It does not change anything with the top looks the same but feels slicker, water beads on the top but after a day in the rain it will soak in. I usually have a cover on the top but on one day with the cover off a seagull left it's mark (I live in Seaside) with a damp it just wiped off! I also applied it on my seats (I have the base model)
Check it out
Stainz-r-out NANO QVC

Frank
Seaside, NJ.

 

the place i work at uses that stuff for upholstery products and it actually does work. so i bet it would work on the top. i'd be careful with fading in the sun though the chems inside it after a while break down.