If the car was a personal car, you only report it if you have a gain on the sale.  

A loss on the sale of a personal asset is not deductible. 

Cars typically go down in value after you purchase them that is why few personal care sales are reported.

Now if this is a business vehicle, then it is reported in the section where the deduction was taken under the Vehicle expense area (fro example Rental, or business schedule C, or Farm schedule F)

To enter your Car sold (if you made a profit)

Click on Federal Taxes

Click on Wages and Income

Click on I'll choose what I work on

Scroll down to Investments

On Stocks, Bonds, Other, click the start or update button

Goes under Other with purchase date, purchase cost, sales date and sales price all entered.