The average amount of negative equity in an existing auto loan is about $3,600, Power Information Network says.

The percent of buyers with negative equity has been creeping higher since 2011. But that’s not entirely bad news for retailers because it indicates customers with lower credit scores are getting financed, Power Information Network says.

For the first quarter this year, 25.9 percent of new-vehicle loan customers who had a trade-in had a trade-in with a cash value lower than the payoff amount on their old loan, up from 23.6 percent a year earlier, PIN data show.

“What we’re seeing is that negative equity has increased along with other metrics we see moving in lockstep with each other,” says Thomas King, senior director of PIN.

“A good example is we continue to see a rebound in sales to consumers with lower credit scores, and people with lower credit scores tend to have more negative equity,” he told Automotive News.

The percent of customers with negative equity hit a recent low of 22.2 percent in the third quarter of 2011. In the third quarter of 2009, when the cash for clunkers program paid a bounty on less fuel-efficient trade-ins, negative equity dropped to only 14.8 percent.

Negative equity typically means the customer needs to roll the negative equity into their new loan. Currently, the average amount of negative equity is about $3,600, King said.

Of course, being upside-down is a bad thing if the customer can’t afford to refinance their old loan. Through the recession and the slow recovery, negative equity has served to depress new-vehicle sales because people stayed in their old vehicles, lenders and analysts say.

However, King said financing a reasonable amount of negative equity might not be such a bad deal in part because most new cars get better gas mileage than the cars they replace.

Over time, the fuel savings can offset the negative equity, he said. It also helps that interest rates are low, he added.

“This is a good time to get in a new vehicle,” King said. “You get a new product with a warranty and a lower cost of ownership. You get in a new loan at a low interest rate, which helps with the payment.”