They should make it an instant rebate instead of a tax credit. Many people (probably a majority of people in the US) don't have enough tax liability to take advantage of the full $7,500 credit right now. Plus you have to wait until next tax season to get your money which is another obstacle for middle income families. I've read where there's been some fraud with the tax credit too--some guy bought a Hummer or something and tried to claim the electric vehicle credit!
Don't get me wrong, the $7,500 is great and many people do qualify, but if we really want to get electric vehicles into people's hands then make whatever amount an instant rebate. The bigger the better!