All 2007's did not sell with a $10K ADM.
I know where there is a brand new 2007 sitting, right now and it doesn't have any ADM. He's trying to get the 2007 MSRP for it and it's been sitting in his showroom for a couple of years now (after sitting in his storage for a couple of years). It won't sell at MSRP and I think he's CRAZY for trying to get it. He bought it on speculation and he got burned by putting it in storage (which cost him money) and thinking the price would go UP, rather than down.
Ya win some, ya lose some. He's gonna lose more because he's being stubborn.
But my point is, all 2007's didn't sell for $10K over MSRP and in fact some sold for back of book/MSRP.
The dealers that put ADM on their cars had the ability to negotiate below MSRP (about $4-$5K, without losing their hold-back) so they could sell them or sit on them. It was their choice. If FoMoCo charged the dealers $10k more for the car, they wouldn't be able to negotiate the price down and there would be a TON of unsold 2007 GT500's sitting on lots across the country.
How many dealers would buy any 2008 GT500's if there was a surplus of overpriced 2007 GT5's laying around? Not many, if any at all.