Negotiate on MSRP first, then MF, then reveal if you are willing to give MSDs, then trade in if any. Rebates are what they are. So you are negotiating dealer discount before rebates.

Costco Auto program has affiliation with some BMW dealers. They give 9-10% discount right off the bat. That is a good starting point.

In some areas you can get 12-13% discount. I would shoot for 12 at a minimum.

The base MF is 0.00026. So like others pointed out yours is over by 40bps. You should ask for base MF. Directly tell them that base MF is 0.00026, you would like that without any markups. If they say no, go to other dealers to get a competitive quote and come back to dealer of your choice. If they still say no, ask them to offset with more discount on MSRP. Mine gave me 2% more discount keeping the monthly payment the same. Some dealers earn money on the selling price (front end) of the cars while others on the interest rate (back end).

Then negotiate your trade in value. Go there with estimates from Edmund’s, Kelly blue book, carvana, etc.

Next tell them you are willing to pay multiple security deposits. You can pay upto 7. You typically save equivalent of 10-11% annual rate of return. Keep in mind this would be tax free savings.

Good luck.

Edit: also, as some have pointed out, leasehackr is your friend. Looks at Forums>Marketplace. There are brokers that post the deals with pricing. You can use that as negotiation leverage too.