YMMV, but for those of you trying to make a decision on trading vs selling their cars, I just took my car over to CarMax for an appraisal.
It's a 2017 BMW 330i xDrive, with 19,000 miles. It has both the full factory warranty, and a BMW CPO warranty that's good until 2022. The list of options and packages is long, so I won't go into it. I'll just say that the retail KBB on the car in excellent shape is around $38,500. And I added BMW performance brakes, ($2800) installed by the BMW dealer at 14,000 miles.
The appraiser didn't ding me on anything. In fact, he told me it was the cleanest car he'd ever appraised, and said that he'd like to buy it himself if he could afford it. Then he proceeded to give me CarMax's offer: $25,000.
Needless to say I won't be trading in my car.