2013 BMW 528i XDrive Engine very sick

Yes, there was an issue with the N20 4 cylinder engines which involved the timing chained guides breaking part duet a worn tensioner. BMW added an extended warranty for 7 years or 70000 mile when mainy owners complained and had to replace engines. You are just out of that warranty. Is the $16K and $8K the prices you were quoted to have a used engine installed? Is the $8K from a BMW independent garage who have done a swap already? Then I would go that route. You can get a personal loan if you had to pay finance it. The BMW price is too much. I personally only like to deal with a dealer when the car is under warranty, yours isn't. Your last paragraph, are you asking if the dealer will buy your current vehicle for $8K that has a damaged engine? You will still owe $7K if you have a $15K loan. Are you saying you will roll that into another car loan? That isn't a good idea, as you will be upside down on your car loan. Gap insurance and maybe a higher interest rate will add extra costs. Fix the current car, and drive it for many years way till the loans are paid off. Maybe even drive it a few more years with now auto loan payments.