Don't expect a BMW dealership or BMW salesman to comment here on the proposal of another dealership or salesman.
Car dealerships are free to charge whatever they want for cars, and pay whatever they want for trade-ins. You're also free to offer what you want for buying cars and to ask for whatever you want for your trade-in. It the dealership's and your numbers end up the same, a sale is made.
If you choose to trade in a car, you're going to get a lot less than what you'd get to sell it yourself.
With the current inflation, MSRP changes are going to be more frequent now. Pricing guides can have obsolete information. "Build" your car on BMWUSA.com to find out the current MSRP for the base model and for options.
Car manufacturers don't publish "dealer invoice" prices anymore. They did the last time I bought a new BMW, March 2018. At the time, "dealer invoice was 93% of the base model MSRP, 92% of options' MSRP, and 100% of the transportation fee ($995 for BMW's the last time I checked).
I'm willing to pay for good service. The better I'm treated, the more I'm willing to pay for a new car.
My first offer for Frau Putzer's 2018 X3 was to split the difference between MSRP and "dealer invoice," not including the incentives I'm eligible for. BMW of Bubbavile (BMWoB) took my offer. One of the provisions of my offer was any "processing fees," would come out of their side of the equation. There were a lot of incentives at the time, including one for $500 from BMW FS for having their credit card and financing the car though them. I also had $1200 in points on that credit card. BMWoB took my first offer without a fight. By the time the dust settled, I paid 11.37% below MSRP, before all the legitimate fees (sales tax, DMV fees, Floriduh WTF fee (WTF?) of $6.50, etc.
With the car shortage, BMWoB was charging over MSRP for new cars the last time I was in there. They also had very few new BMW's in stock. For some reason, they had more X7's that 3 Series in stock. They also had very few car salesmen.
I've had trouble with new cars' clearcoats being scratch by the minimum-wage persons who wash cars at dealerships. So, my new rule (part of "good service"), the "Putzer Protection Plan," is that my factory ordered new cars are presented for delivery unwashed with the shipping film still on them. It a dealership doesn't like this, e.g. Honda of Bubbaville, Hyundai of Bubbaville, GM of Bubbaville, I say "O.k." and start walking toward the door to the parking lot without saying anything else. That's how Frau Putzer ended up with a BMW instead of a Honda, Hyundai, Chevrolet, Buick, GMC, or Cadillac.
My plan is to replace my cars bought new when they're ten to twelve years old. The window for replacing my 2014 535i opens up a year from now, and I'm looking forward to a new car. If market conditions are favorable, nest year I'll propose my long-standing offer, to split the difference between "dealer invoice" and MSRP, so about 4% off of MSRP with me getting any incentives available. It they take it, fine. If not, that's fine too. I'll tell them "We'll try this again next year." I could keep my 535i 13 years if I had to, before it will need new tires and a new battery and go over 100k miles.
My 535i will likely be worth around $10k by this time next year. FSBO-ing a $10k used, well maintained, ten-year-old BMW is fairly easy. FSBO-ing a $35k, three- or four-year-old BMW isn't.