Lots of people will tell you how well they did and how cheap they got it. "Went right to Charlie", they say.
The simple truth on car deals from my observation is get what you want (need), and through research, come up with what you want to pay.
Know your loan situation on your trade and realize if you're upside down or have mediocre credit, everything ends up worse.
Don't get pressured to settle. Don't get roped into dealer installed stuff like rust proofing, etch, or the like.
Also realize they are in business and have overhead so if you present reasonable numbers that favor you and stick to those numbers or come close, buy it and walk away happy as you got what you came for.
People will ask what you paid. None of their business. They will all claim they could do better. Don't worry about it.
Also factor in the relationship with the dealer for things like service. That's important.
Better yet. Get to the age where you can pay cash, because not having that payment is a blessing.
How to negotiate with the car dealership - NY Daily News