Answer the plates belong to owner, If you take the plates back to your county court house, and there is any time left before the license expires you maybe able to get a refund on the license fee you paid.

Answer About 10 percent would be considered okay

Answer Goodwill and the Kidney Foundation accepts cars as donations.
The former uses proceeds from sale to help make disadvantaged (displaced workers, physically-challenged) more self-sufficient through such ways as job training/placement programs. The latter helps those who need kidney dialysis and to fund kidney research. It's admirable what you want to do.

Answer get in touch with you local fire service they use scrap vehicles to practise rescue situations and i think they will also collect it from you.

Answer First of all, you can only deduct a charitable contribution if you itemize, so if you don’t itemize, there’s no tax benefit to you from the donation.

Charities usually sell donated cars at auction, and they’ll give you a receipt for the car showing how much it sold for – that’s the amount you can deduct. Be aware that cars being auctioned usually sell below what would be fair market value.

The tax benefit from the deduction is at most the amount of the deduction times your tax bracket. So if they sold the car for $3000, and your tax bracket is 15%, your tax savings would at most be $450.

This is for federal taxes, so the rules are the same in every state of the US.