<prompt> Human: I am new to car buying. How can somebody negotiatehaggle the price of a car at a dealership? Is there documents one can take?---Edit:So I went to the dealer. The car I want is a Ford Mustang 2015 or 2016 Ecoboost Premium. I like the I4 and having a turbo.Either way, I went to a dealership. End of the month. I saw the mustang I just described with 11k miles for 25,000 dollars. I knew that was above average. I brought with me what other dealerships prices were, a kbb and I had researched that car for months. The dealer was very condesending. He was trying to make me feel like I knew nothing. I knew it was not a good deal. Not even a fair one. I asked I would take it if he lowered it 2k. He didnt even try to talk to the manager. I just walked away.. I am buying the same car, even same color only 10k miles more through a private party. I am buying for 18,000. Plus, no tax or fees. What does everyone think.  <response>: I am a dealer.The best advice so far as been to read the FAQs over at raskcarsalesGoing in and expecting a flat discount of X or X off is absolutely foolish. Do your research, the tools are right there on that subreddits FAQ and then make an informed, intelligent offer and be prepared to buy RIGHT NOW.I have a Cadillac store. Want 2,000 or even 10 off of a leftover 2017 XTS? Sure, Ill do that HAPPILY! Youd be overpaying by thousands and thousands if you made that offer but wed sure be glad to accept it. I also have a Nissan store, want 10 off a new GTR? Nope, not happening, thank you and good luck but have a nice day.Figure out what a good deal, a target price if you will, should be and back the offer up: TrueCar has this car for 17,200 and I know they charge you a fee so Ill pay you 17,000 for it and take it home right now.Say the car has a 18,100 MSRP and youre out there trying to get 1,800 off and say a really good deal is 17,000. You could spend an entire weekend shopping for a price of 16,300 thats never going to happen, meanwhile the guy at store 2 who said Look, I cant do 16,300 but Ill do 17,000 and thats it would have saved you tons of time and aggravation. 