If the prize was awarded in 2015, you have to include the income and 1099-MISC on your 2015 tax return.
You don't have a loss (in fact, if you try to claim a capital loss on schedule D you may get audited.)
What happened is, the 1099-MISC was issued for more than the true fair value of the prize. This is fairly common, I read a tax court case once where someone won a necklace from Macy's and received a 1099-MISC for the "retail price" of $5000. They had it appraised at around $1500, and Macy's eventually admitted that they never sold the necklace at the $5000 retail price, it was always on sale for somewhere between $2000 and $2500. The taxpayer was allowed to claim the appraised price of $1500 on their tax return even though the 1099-MISC was for more.
In your case, if the dealer bought the prize from you the same day you won it and the vehicle was in the same condition (same mileage, you didn't drive it, still new etc.) then the dealer price is the true value of the prize.
There are two ways to approach this in Turbotax. One way will definitely get you a letter sent from the IRS asking for an explanation, the other way only probably will get you a letter.
A. Enter the 1099-MISC but change the price to the true value of the car. This will get you a letter when your figures don't match the IRS computer. You would respond by showing proof that the true fair market value of the car was less than the 1099-MISC amount.
B. Enter the 1099-MISC for the full amount. Then go to the section for "other income" and create an adjustment entry. Call it "fair market adjustment" or something like it, and enter a negative number price adjustment that will lower the 1099 amount to the true value. This way, the 1099-MISC will match in the IRS computer, and they only might send you a letter asking to explain the adjustment, instead of definitely sending a letter asking to explain the difference.
You may be thinking of a different procedure where you report the car as if it was investment property on schedule D. You would pay tax on the full price of the car from the 1099-MISC, then report a capital loss with the purchase price being the 1099-MISC value and the sale price being the amount you received, creating a loss. The problem with that scheme is that capital losses are not allowed on personal property, and the IRS is likely to assume that a passenger car is personal property and not an investment. So while this will get you to the same end point, it is also likely to end up with a letter asking for an explanation. I have never seen the capital loss procedure mentioned for this situation before.
No matter what you do, keep proof of all your facts and transactions with your other tax papers for at least 7 years.
