Just discovered this. USAA is ending their Bonus Cash for BMW and other manufacturers, as well as their Car Buying Service, next week on Sep 30th, 2020.
https://www.usaa.com/my/car-buying-selling/faq
There's details there. You can get a Bonus Cash certificate now, and still use it through the end of the year.
Now, PenFed (Pentagon Federal Credit Union) has the exact same service and Bonus Cash offers, also through TrueCar. Can continue to do that.
Bonus Cash is up to $4k (which it appears you don't have to use a loan or Car Buying service to get), or $11k if you go for the i3. Lots of members here have taken advantage. Use it while you can!