I've had more luck negotiating with a monthly payment in mind. I know what my trade is worth, how much I can put down (easier if you can just answer zero), and

I've had more luck negotiating with a monthly payment in mind. I know what my trade is worth, how much I can put down (easier if you can just answer zero), and what I what to pay for the car. After my first visit where I learn exactly what car I want; the rates for the captive finance company (which are usually the best). I can do the math to figure out monthly payment for the price I what is at that point. Then I just negotiate using that number, if they bump up the trade allowance or reduce the price of the car it really doesn't matter. I precompute a few numbers to know where we are (e.g., Invoice, Invoice + 3%); but also know the cost of a $1 worth of financing so that I know how much they're charging me during a back and forth.