It used to be that when you bought a new car, the new car dealer invoice price would firmly set its price, and it was up to the buyer to dicker it out with the sales person, and try to get the car at a lower price. The situation is still the same, but now with the Internet, you can shop online, and get quotes from competing dealers that may put more ammo in your arsenal so that you can negotiate a better deal on the new car dealer invoice price.
Before you go to the dealer, get a quote from a couple of competitive dealers, and print those copies and bring them along, so that you have negotiating points. You will save time going from dealer to dealer by doing this, not to mention the hassle factor of negotiating with stubborn sales people whose best interest is to sell you the car for more money. Not many car sales people are on food stamps, so the new car dealer invoice price that they quote you has all the possible markups in it that they can justifiably think up. Good luck!