So, if my buyback from VW is taxable, how do I figure what is taxable and where do I put it in my tax return?

Do you have any form, such as a 1099, reporting the buyback?

No, I did not get anything from them

Only the amount of the buyback that was more than your basis is considered taxable. If the vehicle was only for personal use, the basis is your purchase price. If the buyback was as much or less than what you paid, the buyback is not taxable and not reported on your return. 

If you used the vehicle for business, your basis is the purchase price less depreciation. 

If the buyback was more than the basis of a business asset, report is as the sale of a business asset. 

If the buyback was more than the basis of a personal asset, report it as investment income. 

• Open your account and start your return
• Click Federal on the left side-bar
• Click Wages & Income along the top
• Scroll down to "Investment Income" and click Show More (you may need to choose "I'll pick what to work on")
• Click Start (or Revisit) next to "Stocks, Mutual Funds, Bonds, Other" 
• "Did you sell an investment?" Click Yes
• "Did you get a 1099-B?" Click No
• "Choose the type of investment.." Click "Everything else" and Continue
• Follow the screens to enter the information.
• You will need to enter the date and value when the vehicle was purchased. 

Below is more information:

https://ttlc.intuit.com/replies/5843218