Easier credit is good for auto retailers. Lenders are loaning more money vs. the value of a given vehicle. But for a lender that means a bigger loss in case of a default, Zabritski said.
Experian reported last week that the average amount per unit charged off for defaulted loans grew to $7,401 in the first quarter, up about 10 percent from the corresponding period a year earlier. Zabritski said lenders are getting somewhat lower prices for repossessions sold at auction.
Separately, auction firm ADESA said the average used-vehicle wholesale price in March declined 5.6 percent from a year earlier, to $10,028. In April, following a typical seasonal pattern, the figure increased slightly to $10,096, but that was 4.5 percent below April 2012, ADESA said.
Lower used-vehicle values cut both ways, analysts said. Lower values make used cars more affordable for dealers and for consumers, but in F&I, lower trade-in values also make it more expensive for a customer to finance a new purchase.
According to Experian Automotive, all lender types -- banks, captives, credit unions and independent finance companies -- experienced an increase in the average per-vehicle write-off for bad loans in the first quarter.
But only independent finance companies, which are mostly subprime lenders, experienced an increase in the rate of repossessions. For independents, the repo rate was about 1.8 percent for the first quarter, up from 1.2 percent a year earlier, Experian Automotive said.
The other lender groups were all well below 1 percent and down from a year ago. The increase for independents was large enough to cause an increase in the industry average, to 0.5 percent of outstanding contracts from 0.4 percent a year earlier.
"This is not an unnatural increase," Zabritski said, "considering the steady increase we've seen in subprime lending."