If you are not a business, ownership of a car is not reported on your tax return. In some states, you can deduct a portion of car registration fees or personal property taxes based on the value of the car. Just enter the taxes paid, you don't need to identify which car.
If you own a business and the car is used for business, you need to report that the previous car was disposed of (sold, donated, whatever) and you report the addition of the new car as a business asset.
