I have had my car since new too w/ over 237K miles. IMO, if the car is not causing you any financial stress, you should keep it. I kept my car in the dark days of unemployment and near bankruptcy in the 90's. It was the only thing that was constant and positive in my life back then. To this date I can not imagine any other car that can replace it with. As far as the BB value....you may get low balled by all except a seriously wealthy collector. Someone in another forum stated M5's can be bought as cheap as $4K now and w/ another $15k liquid cash, it can get a rebuilt engine with some money left for other mechanical/cosmetic improvements. I agreed. Search your soul and if the M5 does not suit your life then by all means let someone else DRIVE and Enjoy it! I'm sure they will appreciate the care you have given it. Good luck