The vast majority of cars bought through (Your) Cash for Clunkers would have been bought anyway, which means (your) $3B contribution works out to roughly $24,000 per extra car sold.
Note: this calculation does not account for all the value lost by the forced destruction of turned in cars, their engines and parts.
Additional note: some of the vehicles clunkers were traded in for include Hummers.
And this gets called a “successful program.”