First of all, the Feds don't have a rebate. It is a "gross taxable income reduction (or deduction)"
2ndly, you don't apply for it, you claim it on your income tax return.
3rdly; I'm assuming, you bought a Toyota, since you asked in that category....so you need to read the following link all the way through ( Toyota incentives have been reduced, depending on when you bought your Hybrid)
And Finally, Here's the link:
http://www.hybridcars.com/federal-incentives.html
You may be able to qualify for additional state benefits. Check with your states IRS office.