Last two new vehicles I bought I used the Consumer Reports process- they tell you every price the dealer pays for the vehicle, various options etc plus all dealer programs that cut the costs for the dealership and tells you what you should pay for the vehicle.
I called around asking who would meet X for the price and if they said no (a few were belligerent ************** ("I'm not selling it for that! I have to stay in business.") Yep, you do, just not on my dime).
Once I found a dealer willing to meet that price it was easy and I went with them.
The only time I use dealer financing is after I have gotten agreement on a price AND if the loan rate is a super low rate (with my Yukon I got 0% for 5 years, so yeah, I let them do it.
ETA Actually that's not entirely true- I did a lease then purchase for a car in the 1990's, the NPV of doing that then buying the car at the end made sense. I was on the road about 40k per year but told them 10K on the lease payment calcs. I was 100K over the lease "mileage" when I bought the car. But it made sense at the time based on interest rates. And also the sales tax which here in MA is 6.25% so better to have it applied "monthly" to a lease payment given the lower interest rate they were using to determine the lease than my "hurdle rate" I was usingto compare. Bought two cars that way now that I think about it. I'll explore all options. Especially as I'm going to drive vehicles until they're piles of rust. My goal is when the donation guy comes to pick it up (usually get more for the deduction than a "trade value") he needs to sweep up what's left and take it away. Ha.
But yeah, dont give in to their BS.