It's not just fuzzy math, it's fuzzy logic too.
I'd really love to see the actual questions they asked. Nobody would argue that 'not buying' is never blamed on the program. But there are many reasons people bought cars. Also, just buying or not buying isn't the only purpose here. If there was momentum created, or even just making people buy early could save jobs, prevent plants from idling, etc.
People said they would have bought one anyway. "Okay, when?" should be the next question, because an answer of "Probably soon" should disqualify them.
If you only count the people who said I wouldn't have bought without the incentive, you completely bias the survey because you've thrown out all the 'yes. soon...i think...oh, in the next few months...maybe...' people.
Since cars aren't an impulse decision and we're money-strapped as a Country, it's inevitable that most people who bought were already in the probably category. But that doesn't mean they wouldn't give credit to the program. Maybe they would have been turned down for financing on a higher amount. Maybe they would have gotten to the dealership and gotten sticker shock.
This article is a non-statement. 30% off my favorite hamburger joint would probably make me go out for dinner instead of cook like i planned. Realizing a coupon had expired would make me turn around and go home. I don't shop for cars like that. Where's the surprise in that?