The proposed cash-for-clunkers program strikes me as yet another marginally effective policy that coulda been a contenda. In the aggregate, getting rid of clunkers doesn’t do much good, because fleet fuel economy has not improved in the last decade (at least current proposals don’t target age). Only transaction costs prevent wholesale shuffling of vehicles to yield advantageous trades that don’t improve total fleet efficiency. Clunkers that are cheap enough to scrap for a tax credit likely have low utilization; if they’re replaced by a new vehicle with high utilization, that doesn’t help. It might be a good stimulus for automakers, but you can’t get to a low-carbon future by subsidizing new carbon-consuming capital. The credits proposed in House and Senate versions appear to suffer from MPG illusion:
How many climate and energy policies that don’t work do we really need?