$22,395.68. Seriously, values vary by area and timing. The best way is to go to Edmunds.com or kkbb, etc. and find the highest re-sale. They show private sale and trade-in values. Then put it on the market and see if you get offers. If you get zip you are probably too high for your area. If your goal is a trade-in, what they give you they take back in the price of the new car or vice-versa. Better to settle the used price and then negotiate the new. You will nearly always do better with a private sale than a trade. The dealer has to service/prep your trade and add profit. A BMW dealer may just want to wholesale your Jeep out as too much out of his demographic.
PS. As the owner of two BMWs just be aware that certain models depreciate heavily, especially the 6s and 7s, from new. Used helps but still really depreciate and expensive to maintain. Great handling cars, though. Not so good on the trails