Originally Posted by fongpi
What if I get them to agree to show me their paperwork after I sign papers? It would have to be a verbal agreement of course. And I probably won't be able to do this at a BMW dealership per say, but probably at a used car lot.
If I was selling a car and I knew that it was overpriced, and someone was willing to pay the amount I'm asking as long as I "show my cards" at the end of the deal, why not? Sure, I'd be willing to tell reveal this information...
They wouldn't show you even afterward because even though you can't change your offer, it might affect what you say about them to friends, in online reviews, etc, like "They totally gouged me" or "They had X% profit margin even after I negotiated $X below their asking price, so if you go there push even harder."
Besides, their true cost isn't easy to determine anyway. They have to factor all of their operating costs into the cars they sell, so it's not as simple as what they paid for the car. People have entire businesses around helping other companies just DETERMINING what their true cost of goods sold is, never mind how to reduce said costs.
It's not for you to determine how much they're "allowed" to profit from your purchase, or even know, nor should they feel obligated to limit their profit margins. You get to decide what you're willing to pay, and they decide what they want, both of those determinations based on supply and demand as others have said.