The WSJ does a post-mortem:
Remember "cash for clunkers," the program that subsidized Americans to the tune of nearly $3 billion to buy a new car and destroy an old one? Transportation Secretary Ray LaHood declared in August that, "This is the one stimulus program that seems to be working better than just about any other program."
If that's true, heaven help the other programs. Last week U.S. automakers reported that new car sales for September, the first month since the clunker program expired, sank by 25% from a year earlier. Sales at GM and Chrysler fell by 45% and 42%, respectively. Ford was down about 5%. Some 700,000 cars were sold in the summer under the program as buyers received up to $4,500 to buy a new car they would probably have purchased anyway, so all the program seems to have done is steal those sales from the future. Exactly as critics predicted.
[...]The basic fallacy of cash for clunkers is that you can somehow create wealth by destroying existing assets that are still productive, in this case cars that still work. Under the program, auto dealers were required to destroy the car engines of trade-ins with a sodium silicate solution, then smash them and send them to the junk yard. As the journalist Henry Hazlitt wrote in his classic, "Economics in One Lesson," you can't raise living standards by breaking windows so some people can get jobs repairing them.