It appears that the program was launched before being vetted completely via the EPA's gas milage standards, which are being used as the benchmark for eligibility under the program. Magically, many models that were eligible for the discount now aren't quite gas-guzzly enough to qualify. Many people who were about to take the plunge and trade in their old car found out recently that many models the EPA listed as getting 18 m.p.g. (which qualified said models) now get 19 m.p.g., making them ineligible.
I never realized that fuel economy was so malleable; why can't we just say everything gets 50 m.p.g. and be done with it. We'll be free of foreign oil in no time!
The EPA says that upon further review, just as many models were added to the qualifying list as were removed. I'm pretty skeptical of that, but maybe if they announced which models were added and which were removed....
Oh, and what about people who have already traded up and are now expecting a credit for a car which no longer qualifies? According to the National Highway Traffic Safety Administration (who is administering the program), too f'n bad. All sales are final and no money back for you.
Boy, the government is great at running these types of programs. If only we could put it in charge of heathcare.