Not sure why anyone would give up $4-6K difference in trade in value Tesla vs Carmax, etc. unless it happens to make sense on the sales tax side. For me, when I last figured it, the sales tax difference was $2K so $2K-4K better off to go to Carmax.
Those of you who are keeping your trade ins, loan info alive, I would suggest you just change to cash and figure those things out when you actually have a VIN. EDDs fly around so much that the odds are however the numbers crunch out now, trade in values and interest rates will change by the time you get your car, unless it is next week.