Yes you’re missing trade in tax credit in some states ( Arizona is one ). I did the same thing as OP and was out nearly the same, after taxes.You factoring in paying taxes on two new car purchases? I would think that your 2020 would need to appreciate in value by $2,000-8,000 (depending on your local sales tax) in order for you to only be out $1,000. I live in an unincorporated county, and sales tax is around 3%, but within city limits it is 8%. Let's say your tax rate is 5%, and the JT costs $50,000; that's $2,500 in taxes on each new car purchase (for a total of $5,000 in taxes). If you are only out $1,000 then your 2020 appreciated in value by $4,000? Am I missing something here?
Not all states have that of course !