It used to say you can claim the tax credit now, but you must keep the car 3 years. If you sell the car after 1 year, you pay 2/3 credit back.
If you sell the car after 2 years, you pay 1/3 credit back.

IRS figures nearly all people would keep the car 3 years.
But, this is basically based on the honor system.
( and the occasional audit! )

But I have not re-read the laws recently, as I have not bought a hybrid recently. Check for state incentives also. My state incentive was better than the IRS one, and has nothing to do with AMT.