I don't think they would fit... I checked out a G35C over a year ago, when I was deciding between the Z and the G, and I think I remember the seats from the G being wider and thicker then the Z seats. I think the Z seats are a little more sporty, while the G seats are a little more luxury, and hence a little wider and thicker... Not sure though.
I'm also interest in this. Does anybody know for sure wether they fit or not?