Talked to two dealers about trading in both our day-to-day cars and there was a 20% difference between what KBB quotes as the trade in and what the dealers told me was Black Book trade in. One dealer also showed me what my car was fetching at auction and the number is about 20% below KBB. So can someone reconcile those differences and tell me who should I trust more KBB or dealer Black Book?

MTIA