Here are the car buying negotiation tips from the Reddit link above:

Background: I've worked in Purchasing/Supply Chain my whole career and I've gotten very good at negotiating. I started my own business three years ago buying cars for people on the side. It was great because dealerships are open late and on the weekends so I could keep my regular job.

My business works thusly: My clients tell me what they would like to buy (make, model, year, mileage range, or a description of capabilities), I find cars for them, and get them the best offer. They also tell me HOW they would like to buy the car (buy/rent/lease/tradein/whatever). I do not claim expertise on any of these things. This post will focus on NEGOTIATION TIPS. Do not think that this is a guide to get you through the car buying process from soup to nuts. Not even close to that. I don't claim to know the arguments of lease/buy. You'll have to see other posts for that. Sorry for ANY confusion on that topic.

This post does NOT address used vs new or lease vs buy because I am NOT experienced enough on those things to talk about them! My strength lies strictly in finding cars and negotiating the best offer for my client. These are NEGOTIATION tips.

Here's my advice:

1: Get multiple quotes on comparable vehicles/the same vehicle (if new) from multiple dealerships. Always try to get as close to apples to apples as you can. This does two things: Gives you leverage and also gives you a better sense of where the market is at.

2: THIS is probably most important. DO NOT GO IN to the dealership until you have a price and a warranty under which you are willing to buy the car if it's in good condition. They use all sorts of manipulation tactics that ONLY work in person. I won't even go into them because they only work in person. So just DON'T go in until you are ready to buy the car at the price and warranty you've been given. They'll ALWAYS try to bring you in for a test drive and pressure you. A seasoned buyer won't be affected, but the best way for you (or anyone) to avoid this nonsense is to simply not give them the opportunity.

Make it very clear that you will only walk in the door after negotiations have ended. You can even lure them by assuring them that if the price is right, you'll go in, test drive the car, and leave with it that day if it's to your satisfaction.

3: Don't pretend to find things wrong with the car to negotiate. If there's something wrong, tell them to fix it and you'll come back. If there's not anything wrong, don't make it up. Particularly if you're buying under warranty. Because then you'll just look like a fucking sucker. Think of it this way: If you're getting a warranty it is in their best interest to ensure your car is in tip top shape. Because any problems with it when it leaves the lot are really THEIR problem; not yours. Depending on the comprehensiveness of the warranty, obviously.

Basically, making up shit about the car is a very predictable strategy that people try. It's only effective at making you look like a damn fool. You shouldn't have to "trick" them into your price. There's nothing wrong with saying "This is what I'm willing to spend." Nothing shameful about that. So don't waste their time and your time with bullshit.

4: Quote ladder. This is an age old tactic in Procurement that is sort of like the crossbow of buying. In that even a peasant can be trained to use it pretty effectively with very little effort. Remember those quotes you got before? You're going to show the person with the highest quote, your lowest quote and tell them to beat it. If they do, you're going to take THAT quote to your NEW highest quoter and tell them to beat that. And just keep doing that until you don't get anything else. Try to get the mileage and year to be as close to identical as you can so they can't weasel around and make it very clear that if they do not beat the quote, you won't be considering them any further. It lacks nuance, but for someone who's buying their first car, it can save them a lot of money.

5: Don't trust the finance office. If their interest rate seems high, challenge them. Do not buy ANY of the extra shit they offer you. I'm serious. Anything. The sale is not over until it is OVER. If they keep trying to sell you horseshit, threaten to leave. The finance manager is in a predicament because if he blows a sale, he's going to have a very angry salesman hollering at him. They typically back down pretty quick in my experience.

6: If you're making a downpayment try to make it on your credit card. Gets you points and cash back in many cases. Certainly did in mine. If you've got to write a check it may as well be to your credit card company. Obviously only make the down payment if you're not going to have to pay interest on it.

7: Negotiate trade-ins at the end. Don't let them know you have one til after you arrive at a price. And better yet, look into selling your car on your own. You'll usually be able to get a better price. But there's something to be said for the convenience of "I'll give you my car if you knock off three grand." Just know the value of your car and subtract an estimation of the value you place on the time you'd have to invest to sell it. If you can get another five hundred bucks but it'll take you eighty hours of effort over the course of months to sell it, maybe you just take the dealer's offer?

To end, I hope these tips are helpful. They've helped me in my work. I don't claim to be an expert and I had to learn each of these the hard way at some point or another.