Pretending that the dealership is making you a good deal by selling 1500 over invoice is horrible. Large dealership include a "pack" into every invoice paper that you get to see. They sometimes hide it as "advertising" or "shipping" on the invoice. It is neither of those. It is strictly profit for the dealership. On a new car you will pay anywhere from 400-3000 depending on price of car. So if they are saying 1500 over invoice they are making anywhere from 1900-4500 dollars profit.
They also wont want to negotiate as much on the price if you are not financing. They hide even more profit within the financing numbers if you go thru them for financing. Even your own bank will do the same on your financing.
I could type a book on the ways a large dealership makes money.
Example your bank tells you hey great news we can do 2.9% for you. When the bank will actually finance at 1.9%. 1% profit directly in pocket and no one except for dealership or the bank is wiser to it.
I kinda skimmed thru the thread but I dont think the Dr. is financing.