Wouldn't it make sense to trade the old one in for the sales tax savings alone? Even if they offered 2k less than what retail will pay, 6.5% or 7% is nearly 4k in savings.The model Y is the absolute best car I have ever driven or owned, and I have driven 100's as a previous car salesman and have owned quite a few.
I paid $49k a year ago for a 2021 model. Kelley Bluebook is showing $59k for 2020's with 30k miles. Mine is a year newer with 20k miles. I have literally paid less than $10 for electricity for all 20k miles as Tesla gave a free year of supercharging when I took delivery. Taking delivery of a Performance Y in a couple weeks that was $61k at order, now $64k. Should be able to sell the old car to someone near $60k.