I don't know how light weight they are, but the Canadian GE (2009-2013) Fit LX model had these wheels in the 15" size:
http://i90.photobucket.com/albums/k2...sc00811lwh.jpg which look very similar to the 14" wheels on the 1st generation hoda insight. Unfortunately they weren't available in the US.
Aluminum, with the benefit of the very flat face for aerodynamics... perhaps we can come up with another list for highly aerodynamic wheels...