Unfortunately for the Democrats, all this really proves that people respond to incentives. In this case, the incentives merely impacted the timing of car purchases.
Imagine what benefit we could get by incenting people to save, invest, and develop businesses? By, let's say, the radical notion of cutting taxes on savings and investment, and eliminating senseless regulations?
Silly question in an age where “community organizer” is held to be an ideal, and the business people who actually make life better are loathed.