U.S. car owners are carrying higher auto loan balances but still making timely monthly payments.

Auto loan debt per borrower grew 4.4 percent to $16,769 in the final quarter of 2013 from a year earlier – the 11th consecutive quarter to post an annual increase, according to data released Tuesday by credit reporting agency TransUnion.

Even so, the U.S. auto loan delinquency rate ended the last three months of last year at 1.14 percent, below the 1.3 percent average quarterly late-payment rate for every October-December quarter going back to 2007, the firm said.

The trend suggests borrowers with auto loans continue to keep up with payments, even as auto loan debt per borrower has grown steadily. It’s up 12 percent since the first quarter of 2011.

Stable fuel prices, low interest rates and the increased availability of credit helped propel U.S. new car and truck sales up 8 percent to 15.6 million last year. That was the industry’s best year since 2007 and the fourth year in a row sales increased by more than 1 million. New auto loans tend to have higher balances early on, which helps drive up auto loan debt.

Auto loan debt per borrower edged up in the fourth quarter by 0.5 percent from the previous three months. The increase was broad, with every state posting a bump in auto loan debt per borrower in the quarter, TransUnion said.

“Consumers are willing to take on more auto debt,” said Pete Turek, vice president of automotive at Trans-Union’s financial services business unit.

Typically, the late-payment rate on auto loans, credit cards and mortgages rises in the October-December quarter, as many consumers hit the stores to buy gifts for the holiday season. The shopping sprees force them to put off making timely payments.

That seasonal trend also drove up the late-payment rate on auto loans in the last three months of 2013.