Loans to subprime borrowers have reached the highest level since the start of the financial crisis, driven by a boom in auto lending and a new crop of companies extending credit. Almost four of every 10 loans for autos, credit cards and personal borrowing in the U.S. went to subprime customers during the first 11 months of 2014. That amounted to more than 50 million consumer loans and cards totaling more than $189 billion, the highest levels since 2007. Car loans account for most of the increase, totaling $129.5 billion during the first 11 months of 2014, 68% of consumer subprime-loan volume. Americans are also willing to take on more debt; a Federal Reserve Bank of New York report showed total household debt increased $306 billion, or 2.7%, in the fourth quarter of 2014 from the year-ago period, to the highest level since the third quarter of 2010.