I don't know if you are talking about the same thing, but...
You can get a 'prefered supplyer' discount code if you happen to work for someone that supplys 'stuff' for DC. I work for 3M and got a number thru my company that was good for about $6000 off the price of my '03 truck after all the rest of the dealing was done.
We are able to get discounts from work for several brands, GM, DC, Ford, Nissian, Honda, Subaru, come to mind. Each has a different way of figureing it. I got about $1000 off a '04 Chevy Aveo this way. .