I am on a lot of forums, the common issue I see is most people do not know the difference between fact and opinion. Fact applies to everyone and opinion applies to just you.
What I found works for me (when negotiating on a vehicle) is pay cash, either come in with your own money or finance elsewhere, order a new model. Be prepared to walk away. If you trade in or finance I find you loose on the negotiation end. If you buy a hot new vehicle (off the lot) the Dealer usually has money invested in the vehicle so I found I do better by ordering. This does not apply to old stock that they need to move.
I ordered a 2018 Hellcat when the 2017's were selling for 5k over list, I paid 3k under list. I ordered a 2019 Raptor for 6k under list, the second Dealer came to the table, first one wanted full list and they would throw in a spray in box liner. I checked with a third Dealer as they were closer to my home, but no go, they would only do about $800.00 off.
I got a lot of negative comments about bucking the norm, that said its my money, I worked hard for it so I will spend a few hours researching before I spend it!