Here's four more big ones, all to do with zipping up the deal after youv'e agreed to a price/interest rate:

1. If you are financing through the dealership and you've agreed on an interest rate, they usually have not secured financing by the time you leave the dealership with your signed paperwork and the car. There is usually a place in the contract where they have filled out a interest rate "range" (e.g. "2.9% to 5.8%) that they are guaranteeing. They will have based all of the numbers on the lowest percentage rate in that range. If they are not able to get the lowest rate, or can get a better spiff from the loaning institution by hitting you with the highest rate in the range, they will do so, and you will get a call in the next few days to let you know that either your payment is going up, or you need to bring in a lump some to add to the down payment. It's perfectly legal and legitimate, because no matter what interested rate they based the calculations on, if you signed the document stating that you accept the fact that your interest rate will be somewhere in that range, all of the other numbers go out the window, and all the fine print in the document legally supports that.

2 The Waiting Game - This one is simple - when the hook is set and they know you will likely be buying the car, they will make you wait, whether the finance manager is available or not. Making you wait an hour or two softens you up, makes you in a rush, makes you tired, impatient, so that when you get in the finance office you are way more likely to overlook a line item, agree to an add on just to get out of there, or lose your composure in general during the most critical part of the negotiation where you need to retain focus, patience, and tolerance of their relentless scumbag tactics.

3 - Premature printing of contract - Finance manager will be very quick to print an incorrect contract with add ons or numbers you didn't think you agreed to due to their constant tricks. The fact that he prints the long contracts, several of them, in quadruplicate creates a sense of subconscious finality in the mind of most buyers. Some people simply do not have the intestinal fortitude to say, "uh, no, you got this and this and this wrong, you are going to need to change these numbers and remove the GAP insurance and reprint". The last car I bought he had to reprint 3 different contracts 4 times, each time making an error in the dealership's advantage. He was easily the snakiest one yet.

Embarassing the Buyer in front of SO, friend, or child - If you have a person with you as "backup" that you have brought to help you negotiate, you may think that having a two on one scenario works in your favor. It does not, even for the most shrewd negotiator. It opens you up to a whole slew of subtle tactics designed to embarrass you, make you look like you are unreasonable or stupid. "Oh sir, it's totally fine you don't want GAP insurance. But in your circumstance I've honestly never seen someone not opt for it. I wonder if you could explain to me your understanding of GAP insurance and just why you don't want it?" Do not fall for this or any other variation of this. You are being baited to enter a debate where you will get your ass handed to you, and you will look like a moron, and either cave to what is currently being discussed, or you will want to avoid looking like an idiot on the next 5 things he offers, and you'll end up getting the $700 undercoat just to keep from getting dragged into a mini-debate that will make you look like a moron. Don't get me wrong, it's not that he or she won't do this to you anyway, but if you have someone else with you, it amplifies the embarrassment you will feel when you try to fumble through an explanation as to why you don't want the Super Motherfucking Clear Coat That No One In Their Right Minds That Lives In The State of [insert your state] Would Ever Not Increase Their Payment By a Measly $12". Don't fall for it.

I hope at least one person reads this and it helps them.

Oh, and just whore for some Reddit Karma, it's my assumption that you will never encounter any of the above at a Tesla dealership. At least the ones the crooks all in on the game will let them open...