"This credit, if transferred to the dealer, when you earn too much income to claim it yourself, would be recaptured and would require you to repay your tax liability accordingly. However, if you do not have sufficient tax liability to fully use the credit if it was included on your tax return, you are not obligated to pay it back. This can effectively make the credit partially or fully refundable for certain taxpayers."

You have to earn under the income limits or you have to repay the credit. However, if you meet the income criteria there is no obligation to repay the credit, though it does sound like you need to sign it over to the dealer and you won't need to repay it, just that it may not be refundable on your taxes if you don't owe enough.