Don't forget that there are OTHER plug-in electric vehicles out there. A $7,500 credit would make a Green EV Triac cost around $12,500.
The Triac: An Affordable Electric Car
Eligability and credit awarded seems to be based solely on vehicle weight and battery capacity.
Plug-in: "uses an offboard source of energy to recharge such battery"
Battery Requirement: ">4 kilowatt hours"
"has received a certificate of conformity under the Clean Air Act"
Allowable credit is then determined by vehicle weight.