NPR today covered a study by University of Chicago economist Amir Sufi and University of California, Berkeley economist Atif Mian that showed that last year's cash for clunkers program produced few if any net new sales. (Read the article here.)
This is an even more negative view than the study conducted by Edmunds that shows a net of over 100,000 sales.
Their methodology is interesting. They looked at sales patterns in parts of the country where clunkers were few, and compared those with areas where clunkers were plentiful. (The Edmunds study looked at market segments that were excluded from the clunkers program, vs. those that qualified.)
Both this and the Edmunds study are trying to compare a possible future with actual events--a tricky proposition at best. Even so, the evidence keeps piling up. While many persist in calling C4C a great success, the data tells a different story.