[Number 3]

Yes, the M3 had (not sure about the current gen) a carbon roof.

Keep in mind, there are two types of carbon. I call them SHOW, where you can see the weave, and cheap where you just paint over it because you aren't using color or continuous sheet. We even used chopped carbon on the floor of the C6 Z06. So to do a show roof would be ridiculously expensive. The paint GM uses on the show carbon for the Corvette is like $1,000 per gallon or something along those lines. But you can certainly bond in a roof panel if you design for it. I just don't think we'll see that on anything short of the Z/28.

So painted CF? Maybe....Z/28 ish. Show CF? Not likely.