The rule of thumb absolutely applies to the big 3. Ram, Ford, Chevy (GMC). There is zero science to it. It's just generally speaking, at any time per year, if you are getting offered anything less than $10k off you are over paying. Period. Get them during a good time and you can expect up to $15k. I've had friends argue with me, and after a lot of prodding, they always come back with the deal I said was possible. Like I said before, none of us have any clue what the dealers pay, not even their employees. It's all smoke and mirrors.
This is not a thesis for my PhD. It's a general "truck buying for dummies guide". It's not a detailed explanation of how to get the best deal. There are tons of those and yet so many people end up thinking they got a good deal when they didn't. Why? Because they think they are "educated" thanks to the internet. I've helped a lot of people get good deals. All of them have read up on the same old stuff..."get the invoice and go from there"..."make sure you know all of the dealer incentives"..."what's the hold back"...it's all crap created by the dealer and factory network to make the consumer think they're educated. It's much simpler if you have a general idea of what discounts are available in what categories. And regardless of manufacturers, you can paint a fairly broad stroke and be somewhat accurate. American cars typically follow the same rules, and then the Germans follow their rules, and the Japanese follow their rules. You can reliably expect the best discounts on American cars.
If you want to play the game and negotiate down from invoice, fine. Just understand, if whatever number they give you is less than $10k off MSRP, at any time per year, you're not getting a great deal. As simple as that.
Quick Addition: When we bought my wife her loaded Platinum Escalade last year, we spent a few days negotiating on it. I used my rule of thumb. $10k+. It was christmas time so I figured $12-15k. Salesman got frustrated and went through all the BS about where the money would come from. They kept telling me they couldn't get there. Too far apart. They'll lose money. In the end, we got $16k off on a brand new loaded Escalade. I ignored their detailed explanations and succeeded by having a general idea of what kind of discount I could expect.
Invoice price is a nonsense number to be negotiating from as magically over the last 20 years the spread between invoice and MSRP has closed by half, thanks to the internet making the number common knowledge. Invoice price is a marketing number dealers use now. See a similar position with more data:
