The conventional view is that auto sales, like other categories of consumer spending, have been sharply and directly reduced by the financial crisis. From today's Wall Street Journal:
The hardest-hit markets since the crisis were ones at the heart of the financial problem -- the "securitization" markets where loans for everything from mortgages to credit-card debt get sliced up and repackaged into complex securities.
The size of the market for securities backed by loans tied to homeowners' equity has shrunk more than 40% since the second half of 2007. The market for securities backed by auto loans has shrunk 33%...
These securitization markets provided as much as 50% of consumer lending in the years leading up to the crisis, says Tim Ryan of the Securities Industry and Financial Markets Association, a financial-industry trade group. "Without [the securitization markets], it's very difficult to replicate the amount of money moving into the economy," he says.
I've been skeptical about this story in general, but let's see how it holds up in this case. (Click the graph to make it readable; I'm still figuring out the mechanics of blogging.)
The top panel shows the real interest rate on new car loans, the second shows the average loan-to-value ratio, and the bottom shows monthly auto sales in millions, at a seasonally-adjusted annual rate. (Source: Table G.20 from the Flow of Funds; BEA via FRED.) The vertical lines mark business cycle peaks. To make the argument clear, here are the same graphs for just the past two years. The gray area in this one shows when the "Cash for Clunkers" program was in effect.
We see a few things here. First, while auto financing clearly did get tighter as measured both by interest rates and loan-to-value (the latter is a measure of credit availability), the decline in sales started first. Sales were already falling by the end of 2007, while there's no sign of tighter credit until August 2008. So while the collapse of the secondary market for securitized auto loans may indeed have caused lenders to tighten their standards, it's not clear that this was a major factor in reducing sales. Further evidence on this point: Auto credit tightened just as much in 2003-04, with no effect whatever on sales.
Second, while lending standards relaxed this past spring (the bailouts worked), easier credit didn't get people into the dealerships. The spike in sales this summer was all about cash for clunkers; once that ended, sales collapsed, even though interest rates remained extremely low and credit availability, as measured by the loan-to-value ratio, remained fairly high (lower than in the 2000s, but similar to the 90s.) Interestingly, dealers seem to have tightened credit standards during the period of heightened demand in July and August; in this case, the real dog was wagging the financial tail.
So as far as cars go, we can conclude: The credit crisis may have contributed to the decline in real activity, but it wasn't the sole or the decisive cause. And now that sales have collapsed, there's no reason to think that credit conditions are what's holding them down. If you want to support the auto industry, give people money to buy cars (or retrofit car factories to build windmills). Don't try to revive the market for securitized auto loans.