I've tried several times to find this info. About three months ago I was told by Chevrolet via email they had no way of collecting that data at this time. Still sounds a little fishey to me...
That definitely is fishy (and BS). They have the numbers, they just don't want to share them right now.
They publish these numbers quarterly for Corvettes for various user clubs and forums, so why wouldn't they have it for the rest of their popular vehicles.
Someone on this board must have insider info on this... we just have to keep trying