I'm a CPA, but too busy at work right now to write much, so I am cutting and pasting from the irs website for you. There is also a credit for the purchase of some hybrid vehicles. I can get you more information later if you need it.
From irs.gov
The American Recovery and Reinvestment Act permits taxpayers to take a deduction for state and local sales and excise taxes paid on the purchase of new cars, light trucks, motor homes and motorcycles. The deduction is available on new vehicles purchased from Feb. 17, 2009, through Dec. 31, 2009. In states that don't have a sales tax, the law provides a deduction for other taxes or fees paid. This deduction is available whether or not a taxpayer itemizes deductions on Schedule A.
The deduction is limited to the taxes and fees paid on up to $49,500 of the purchase price of an eligible vehicle. The deduction is reduced for joint filers with modified adjusted gross incomes (MAGI) between $250,000 and $260,000 and other taxpayers with MAGI between $125,000 and $135,000. Taxpayers with higher incomes do not qualify.