First off,the writer gave correct advice. But let's back up and, having been in the business, take a very long look at buying back a car from a lease. Of course there will be maintenance not paid for with a BMW. You should cost out what a brake job, oil change (probably not covered) transmission replacement, etc. 
When someone wanted to buy out their vehicle I always tried to talk them out of it. Cars wear out, they depreciate, they need more maintenance as they age. Rule one:  never fall in love with a vehicle. Okay, if its a high end one of a kind car or truck, fine. 
My final bit of advice is to research that year and make of vehicle on Edmonds.com. People are pretty faithful with their experiences. Plus, you should find out what the true Black Book value of your car is. It's a car, not your wife. Take that any way you wish.