Starting January 1, 2009, there is a new tax credit for Plug-in hybrid electric vehicles, starting at $2,500 and capped at $7,500 for cars and trucks (the credit is based on the capacity of the battery system). The first 250,000 vehicles sold get the full tax credit (then it phases out like the hybrid vehicle tax credits).
Tax credits are available to buyers of hybrid gasoline-electric, diesel, battery-electric, alternative fuel, and fuel cell vehicles. The tax credit amount is based on a formula determined by vehicle weight, technology, and fuel economy compared to base year models. These credits are available for vehicles placed in service starting January 1, 2006. For hybrid and diesel vehicles made by each manufacturer, the credit will be phased out over 15 months starting after that manufacturer has sold 60,000 eligible vehicles. For vehicles made by manufacturers that have not reached the end of the phase-out, the credits will end for vehicles placed in service after December 31, 2010. See the IRS Website for updated information