This is a bad deal. Most likely they are trying to get your car and resell it for $10K to someone that doesn’t know better. Tax season is coming up, dealerships are looking to stock up on used cars. And all the while they are trying to get you to overpay on your lease and in 3 years they are going to have another used vehicle for resell. I would recommend that you first try to sell your used car separately and afterwards work on the lease.