Curious to hear more about the trade. I found it a frustrating process since Tesla initially said they simply take the average of the three most recent auction prices for similar vehicles. After getting a ridiculous low-ball offer (close to half of the lower end of private sales for similar cars), I queried more and got some data. They were offering me $2k less than the lowest auction price for a car with three times the mileage and few of the same options.
I get that they don't run a used car lot, but I ended up just keeping the car and will sell it privately when I have the time. I would have been fine with the low-ball if it actually reflected how they told me the process works. But somewhere along the way, someone is trying to make a few extra bucks.