Retirement tax questions

Thank you! I don't have to report this on my tax this year since I recently settled. When I file my tax next year,  do I subtract the fair market value what the car is worth now or the fair market value when I file tax next year? What happen if I trade-in my car? And the trade-in value is less than selling the car privately. I can't sell the car because the Fair Market Value is a lot less than what I owed on the loan.