They always have a little leaway on what they have on the lot, rather than having to go get one, because they want to get you out the door today. So if you dont act too eager or explain youre just shopping and you dont need a new vehicle right now they can "make things happen". Maybe say youre thinking about buying in the near future right off the bat, so they have to earn your business TODAY, incentivize you to purchase right now.
I personally belong to a bank that has a no haggle price program that the dealer has upfornt agreed to not complain when I come in with a quote for a few hundred under invoice price. That saved me a couple thousand on my 2LT, because even the options were discounted. So, just play hard to get and walk away, or dont accept the trade in value, ect.. until you get at least the preferred pricing, which is between invoice and MSRP, about $1000 off. Preferred pricing is supposedly what they call the GM employee discount (yeah right, they are going to pay cost) but its also what several credit unions already have no hassle pricing agreements with. So if you belong to a credit union look online for the GM credit union discount program.
Either way I would never pay MSRP, mainly because I will buy a car before I really need it, for example the old one still works fine.
I also just said no about 5 times to the extended warranty, and the price came down from 1800 to 1200. I only got it because we will put 20,000 miles a year on it, so the bumper to bumper wouldn't even last 2 years, if we only did 12000 miles or less a year I wouldn't get the extended warranty, because it would take 3 warranty claims to get your money back if paying $1800. I also walked away from one dealership because the manager was a defensive yet intimidation type person, and there is no reason to deal with people like that. don't let them give you a run around about let me run the numbers again, or see if maybe we can give more for the trade in, ect...if you dont like something just say no, its a powerful tactic. Along the lines of not being eager I dont like sitting at someones desk, so whenever they get up to check something I walk around and let them come to me

They also think we are stupid and incapable of doing math. Dont get sold on a monthly payment, 6 year finiancing is a bad idea, and you end up paying too much for the vehicle over time, and then they try to sell you gap insurance because you will always owe more than the car is worth when you finance the taxes and registration with no money down and for 6 years. If youput down enough to cover taxes and get the loan under the invoice price it even lowers the interest rates you will qualify for.
My banks no haggle no hassle pricing makes it much easier though. Another thing though, if youre not actually able to buy or willing to buy if they do give a good offer then best just to say you have to be somewhere and leave before letting them go through the hassle, and just let the salesman call you if they have a sale or rebate pops up. No reason to offend them by doing all that nonsense haggling if youre not buying. Dont want to waste your own time too, so if they have your phone number they might call with better pricing, without you having to wait on them.