Here is how this works:
- MBFS will not negotiate on the residual value of the car - this is something to discuss with the dealer.
- In spite of what Jeff said about the dealer taking a $5K loss, it does not work that way as the car does not belong to the dealer - the car is owned by MBFS which would either sell it to the dealer, or at auction; the dealer makes money whether you buy the car or not.
- Once the dealer processes the return of your leased car, MBFS would show the dealer, on their website, an offer to buy the car based on its inspection report, but also market conditions etc. To this value the dealer expects to add a mark-up of $1-2K - and that is only if you make clear that you would not buy or lease another MB car from them.
- In your particular case, since the car only has 12k miles, chances are the dealer would be offered a price very close to the residual, maybe even higher.
My advice, if you like the car, it make sense to buy it at the residual value and get an extended warranty from Jeff at MB Louisville or other people revered on MB World, who are offering discounts around 40%. Cars you may find on carmax or cargurus often did not have the battery certification performed, and would no longer have the battery warranty.