Here's the Hybrid scoop:
http://www.hybridcars.com/federal-incentives.html
I guess in 2004 and 2005 it was a deduction. You claimed it on your taxes. It would vary by how much you made. you would get something back no matter what.
For 2006, it was changed to a tax credit. The difference being the maximum you could get back. As a deduction you would always get something back. If you owed $500 in taxes and you put in the $2,000 hybrid deduction, you'd get a $1,500 refund. As a tax credit, you can't go below zero. So, if you owe $500 in taxes and you put in the $2,000 hybrid tax credit, you'd get a check for $500. Anybody who already gets a tax refund, would get nothing.
The other thing that changed for 2006 was that a limit was instituted. The tax credit would only apply to the first 60,000 hybrids sold per manufacturer. Both Toyota and Honda hit that number in 2007 so ..... no more tax breaks for these cars. I'm not sure if that's good or bad. It forces people to buy American I guess but, I didn't even know you could get a tax break on an American hybrid. Either way, I already get a refund so i wouldn't get anything anyway. Hopefully this will change.
I guess it comes down to this. Politically, I guess there is a tax incentive for hybrids. Effectively, there isn't.