The verdict on "Cash for Clunkers"

Guilty of not providing any stimulus.  At all.  The plan only affected the timing of automobile purchases, according to a new National Bureau of Economic Research working paper from Atif Mian (Cal-Berkeley) and Amir Sufi (Chicago-Booth).  The two economists took advantage of the fact that the supply of clunkers varied by city and found that auto sales during the plan were much higher in high-clunker cities than in otherwise similar low-clunker cities.  But once the plan was over, the pattern was reversed.  Exactly.