What on earth do you mean. Have you ever bought a car?
You negotiate the price you are willing to pay. The dealer has no idea if you are leasing, paying cash, or financing. The all-in price is either financed or leased at a specified interest rate. They do not "add in" an up front payment. That doesn't even make sense, and would be incredibly misleading.
If we negotiate $25,000 for the car,and I finance at 0%, you are saying they up the price to $27,500 to "build in a profit"? Nonsense. The numbers are in front of you and you can do the calculations yourself with high school math. 0% is 0%.
You are totally out of your element and shouldnt be providing financial advice. Maybe that's why the dealer rips you off.