If you do some promotion to end users, I feel this could go for well over reg fee, and it's worth the renewal. If you plan to park it and wait for offers to come in, let it drop.
i would guess you would have to wait for there to be alot of used green cars on the market. Plus regular car action houses will be more than happy to action off the green ones too. my vote is drop or quick sale. greencarauction.com (no S) redirects to ibidmotors. possible sale there. greenautoauctions.com is available. Goodluck