Some on Wall Street are worried that subprime auto lenders like Credit Acceptance Corp, Ally Financial, and Santander will soon be in trouble, given reports that a rising share of borrowers with low credit scores are delinquent on their loans.

Auto lenders are behaving similarly to mortgage lenders in the run-up to the 2008 financial crash, but experts say we are not headed into another crisis (more below).

Why it's still cause for worry: Lenders are making fat profits, but there is growing evidence that a significant minority are engaging in fraudulent behavior. Borrowers in many cases have little choice but to pay such high rates if they want to be able to commute to work.

The case for concern:

It's a growing problem : One trend that has propped up this market is lengthening American commute times. As housing affordability in America's economic centers grows worse, the working poor and middle class are being pushed further away from city centers and reliable public transportation.

: One trend that has propped up this market is lengthening American commute times. As housing affordability in America's economic centers grows worse, the working poor and middle class are being pushed further away from city centers and reliable public transportation. What to do about it: Two options are incentives to build more affordable housing and investing more in public transportation.

The case against concern: