Actually, I find the way they set the rebate amount by AER and number of seats to be pretty sensible.
5 seat BEV = $14,000
7 seat, long range PHEV = $14,000 (Pacifica)
5 seat, long range PHEV = $13,000 (Volt / Clarity PHEV)
2 seat & 4 seat BEV = $12,000 (i3 / Smart)
7 seat, short range PHEV = $10,000 (Volvo XC-90)
5 seat, short range PHEV = $7,000 (Audi / BMW / Ford / Kia / Merc / Volvo)
4 seat, short range PHEV = $5,000 (Prius Plug-In)