As a candidate, Barack Obama promised to try and get a million plug-in vehicles on U.S. roads by 2015. In his State of the Union address in 2011, he repeated that number and proposed turning the $7,500 tax credit into a point-of-purchase rebate. That hasn't yet happened, but in the President's proposed budget that was released this week, Obama took another stab at promoting plug-ins: upping the maximum credit to $10,000.

To go along with pushing PHEVs, the budget calls for cutting more subsidies that Big Oil currently enjoys. Of course, the President's political opponents quickly called the proposal nothing more than a "campaign document" that would divide America. Others are proposing that the PHEV tax credit be eliminated entirely.

Getting to a million plug-ins in four years will be tough. Last year, the top two plug-ins, the Chevrolet Volt and the Nissan Leaf, sold just 17,345 units, combined. Add in sales of the Tesla Roadster and the new Mitsubishi i, and that leaves 980,000 or so to go. Do you think an extra $2,500 off the price of the car – plus more models to choose from – will do the trick?