I had the 30 month OC on a '14 BEV that ran out last Feb. My search for fair market value of my i3 for private trade (priced above wholesale, but below retail with extended warranty) put it almost $10K below the OC buyout residual. I called my salesperson and asked if they could negotiate a lower buyout price, and was told I had to talk to BMW corporate. I call BMW, and was told I had to talk to a BMW center (dealer).
I went in and talked to my dealer's general manager, telling him I would like to keep my i3, but was not willing to pay over fair market for it. I told him I specifically asked for him for help getting out of the sales/corporate/sales endless loop. He said he understood, and asked for a few minutes for him to do some research. About 20 minutes later he returned with a paper having a buyout offer from BMW USA with a price about $200 over what I figured was fair market, and I took the deal. I got nearly $5K off MSRP when I purchased, got $7500 back from Uncle Sam, and then got another nearly $10,000 off after the OC was up.
Even though I was buying the car I already had, they still required the lease/OC final inspection, and all was fine with the inspection (I had put on new tires already). A few months later, BWM sent me $300 as a milage credit for unused milage! I certainly was not expecting that, as they had the milage when they made me the buyout offer.