My advice to everyone who asks is to go in knowing everything you can about the pricing, the process, where the profit is, what the deals and rates etc are, then tell them what you are looking for, this forum proves there are lots of dealers willing to give reasonable discounts and if yours will not, then be willing to try another one.
The easiest thing to do (this is not exact but will get you close enough without doing crazy math) is to build it online and get the MSRP.
The dealer makes markup (money over invoice) plus holdbacks and factory incentives etc, so they make ok money at or around invoice - $500 over invoice I would consider reasonable on a new model like this. Any incentives offered by BMW DO NOT come out of the dealers pocket, so are always on top of your best discount off MSRP.
Markup from Invoice is around 7.5%, 500 over invoice is about 7% off MSRP - lots of dealers are doing in and around the 6-7% discount off MSRP according to this thread.
Make a spreadsheet sometimes helps, but take MSPR off the website, then calculate the price with a discount of where you want to start, say 7.5% (the 995 destination is not discountable so only discount the care not the destination). Then on top of that list the current incentives as a further reduction $1000 say for loyalty or APR credits.
That will give you a number you are willing to pay, also make sure you know that rates in your area, if you are leasing, ask them what the Money Factor is, it is 0.00182 (unless your credit is terrible - I think 800 is needed) they may also try to mark up the money factor so let them know you will pay the BMW published rate not marked up. If you are financing, then look up the rate on bmwusa.com - it is 2.89 or 4.35% depending on where you live - you may be able to do better from a credit union or bank, but you will loose any APR credit currently being offered.
You should also put all those numbers once you figure out what you want to pay in here
https://www.calculator.net/auto-lease-calculator.html and this will tell you what your lease or loan payment will be based on those numbers (for the lease 10k miles residual is 59% of MSRP, 12k miles is 58% and 15k miles is 56% - this is off MSPR not what you are actually going to offer for the car - so if car is 100k, the price will be 93k with discount but residual will be 59k (59% of 100k). This will make sure that when they give you the payments you should be without 20 or 30 bucks, if it is 100 or 200 out, then they are playing games and marking something up somewhere.
Post is all up here and lots of people will help - don't be afraid to leave, tell them you need to review and get back to them, be serious, but you don't need to think on the fly and buy it today, if things confuse you, then tell them you are extremely interested, you need to look at the numbers and get back to them in a day or 2 - they will always be there to take any deal they offer, none are so good they won't give it to you the next day.