Interesting quotations you included - where did they come from? I didn't find them in the report you cited. The following is from the conclusion of the Brookings report you cited,

"The evidence suggests that the program did indeed incentivize the sale of more fuel efficient vehicles by pulling sales forward from the near-term future. This resulted in a small and short-lived increase in production, GDP, and job creation. However, the implied cost per job created was much higher than alternative fiscal stimulus policies. ... The CARS program led to a slight improvement in fuel economy and some reduction in carbon emissions. The cost per ton of carbon dioxide reduced from the program suggests that the program was not a cost-effective way to reduce emissions, although was more cost effective than some other environmental policies, such as the tax subsidy for electric vehicles or the tax credit for ethanol."

They aren't saying it was great, but they are not saying it was a failure or that it harmed the industry.

The first link provided above is a Google search URL for the terms "cash for clunkers cost".

Those are article quotes from the front page results.

On the one hand a detailed report and the other a bunch of random quotes.

I think I'll trust Brookings.

Those quotes have details behind them. Such as that sales where mostly all shifted in from the future, less cars where sold overall (hurting the industry), the fuel economy savings resulted in mere single-digit days of gasoline saved over the lifetime of the vehicles sold, and a bunch of other not so great things.

Either way, the Brookings report ends with this quote - "In the event of a future economic recession, we would not recommend repeating the CARS program."

There is a reason for that.