I was thinking it's good to sell a Mercedes at a M...

I was thinking it's good to sell a Mercedes at a Mercedes dealership, turns out it was a joke. I've done all the maintenance in the dealership regularly for 4+ years, detailed car nicely before selling. Wasted 1 hour and they finally gave me an awful quote, probably because I told them I need to sell the car as quickly as possible. The appraisal was done by "AutoNation" which has bad reputation if you do some research online. . Their "boss" even told me "You can try any other dealership or Carmax, and they will give you the same price". I told him this is 6K lower than the KBB price, then he said "KBB is just a guide", blah blah blah, if any other dealer or Carmax gave me significantly higher quote than this, let him know. Well, thanks to his advice, I tried Carmax for the first time of my life and I got the KBB price.The whole process took less than 1 hour, plus they took cared my loan with my bank, and I got the check quickly.

By the way, Dealer only checked my vehicle for like 5 mins, Carmax examined my car thoroughly for at least 25 minutes(e.g. fluid, engine, suspension, etc). They gave me a report about my E-class which of course no issue found (I did Service B 2 month ago, Mercedes's mechanic told me the car was in great shape).

I had no regrets being a Mercedes owner for 4 years, my car never gave me any trouble. I thought our relationship would end happily since I'm moving to Japan for work and I would like try something new there. This experience just made me disappointed.