Many of auto loan debts have been bundled up into asset backed investments. On top of this is the derivative market (aka gambling). Many of these derivatives are OTC ones and are not easy to quantify:
Auto loan debt is the third-largest debt category behind mortgages and student loans. Overall, Americans owe $1.52 trillion in auto loan debt, according to the Federal Reserve Bank of New York, accounting for 9.2% of American consumer debt.
The first domino to fail:
Well, after a lengthy period in which nothing seemed to happen, suddenly the dominoes are starting to fall, and as Bloomberg the used car retailer and subprime auto loan lender, American Car Center, told employees the business was closing its doors, just one day after the company had hoped to pull off a funding Hail Mary by selling a $222 million bond (it failed).