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Auto loans surge, but who's buying may surprise you

American auto buyers are borrowing more than ever, but the people taking out auto loans may surprise you.

The latest data from Experian show the amount of auto loans in the fourth quarter climbed by $86 billion, with the strongest growth coming from those borrowers with the highest credit ratings, also known as super prime.

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"Analyzing the data really does debunk the myth that auto financing is growing just solely in the subprime space," said Melinda Zabritski, director of automotive finance with Experian.

While the percentage of auto loans taken out by those with subprime and deep subprime credit ratings also increased, 3.8 percent and 5.6 percent respectively, they trailed the 7.6 percent boost in borrowing from customers with super prime credit, according to Experian.

Ford Focus
Daniel Acker | Bloomberg | Getty Images

In recent months, the rise in subprime auto loans has fueled speculation a bubble is forming in auto sales, with dealerships potentially selling vehicles to those who will struggle to pay their monthly car payment.

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But in analyzing auto loans, as it does every quarter, Experian says the percentage of loans that are 30 days delinquent is only fractionally higher at 2.62 percent, and the percentage of loans 60 days past due actually fell slightly to 0.72 percent.

"You can make as much speculation as you want, but the data really shows what we see happening in the industry," said Zabritski. "We see growth across the entire credit spectrum."

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Overall, she says auto financing data show a healthy economy where most consumers have a prime or better credit ratings.

Later this month, Experian will release a more detailed analysis of auto borrowing in the fourth quarter. It is expected to show consumers continue to spread out the length of auto loans, with more borrowers agreeing to repay their debt over six and seven years.

Questions? Comments? BehindTheWheel@cnbc.com.