Showroom is right, most of the dealers are full of it. You need to get everything in writing. I had a bent rim when I got the car and the salesguy was telling me how they would take care of it after the sale, if I listened to him I would be out of a rim. I got the damage in writing and when it came around to get a new rim he tried to weasle his way out of it, all I did was ask the supervisor to look at the contract and the salesperson felt pretty bad. Get any favor in writing, any damage that they say they will fix in writing, the time frame of the work, the extent of the work.
Just have the mentality that, if it's not in writing you have no proof and you get any service from them. They are there to sell you a car, not to give away free stuff, if they can weasel their way out of it, it looks good. That's what makes a salesperson a saleperson.
Don't even start with the sale's people acting like they can't do you any favors. Those guys are there to sell cars (pretty outright but they ca mask that pretty well). I like to know how much they get the car for from the factory plus their prep costs so when they give you bull about "we arnt making anything" you can ask to talk to thier boss and show them the figures. You can tell them how much they are making from the car off of you, how much the bank is going to make and so on.
One more thing, trade in's..... Don't let them push you around, it is true that you will not get book vaule on your car but you should be able to get close. If your car runs good and looks as good there is no reason why you need to settle for such a low price. Make sure you tell them this when they give you bull about how much it is going to cost to inspect the car before they sell "it's a state law to inspect everything on the car before you sell it, so why are you trying to cut down on how much you need to give me for the car, you say you need to pay the mechanics to inspect the car, even if you gave me 1.00 for the car, you are paying 200.00 for someone to inspect it anyhow, that cost is coming from your pocket not mine, since when did I have to help you guys inspect and sell the car".
Just catch them in their own lies. I have helped a few friends buy cars, they have saved a few thousand and thanked me greatly. All I ask is for some lunch......
Have fun, hopefully I put you in the right attitude to beat those sales people at thier own game (you can't beat them but at least you don't need to get suckered).