Could paying your bills on time lower your car note? Maybe. That helped consumers snap up cars and trucks at a 15.6 million annual rate in July, about the same pace as in December 2007, when the recession began, and up from a low of 9 million in early 2009. Yet the methods being used to make loans to those with less-than-perfect credit is making consumer groups leery. Some lenders have begun to reach beyond the traditional credit bureaus - Equifax, Experian and TransUnion - to alternative data sources, including some that check a borrower's utility payments and rental history, for information. Advocates of alternative data say the added layer of information they provide makes the lender better able to assess the risk of the borrower. "Including alternative data in the underwriting process increases credit access for lower-income persons, members of minority communities, and younger and older Americans," said Michael Turner, president of the Political and Economic Research Council, an industry-research group. Consumer groups counter that people with limited credit histories often are low-wage workers who may struggle to keep up with their bills. Reporting this sort of information could further impair their already shaky credit, said Chi Chi Wu, a staff attorney at the National Consumer Law Center. A lot of low-income consumers often pay their utilities late, especially in months when the costs are high. And sometimes people withhold their rent because of issues with their apartment," she said. Will these systems take any of that into account? One lender, GM Financial, signed up for LexisNexis's RiskView, a credit score based on utility payments, rental history and other nontraditional data, three years ago as the auto market started to rebound. "Using the RiskView score allows us to approve applications that would otherwise be declined if only traditional credit bureau data were used," said Steve Bowman, GM Financial's chief credit and risk officer. By pulling a wider set of consumer data, GM Financial sometimes can lower the interest rate charged on a loan by 2 percentage points, Bowman said. Although subprime loans represent a small fraction of the auto market, they are the fastest-growing segment. Subprime auto loans, those made to borrowers with credit scores below 680, climbed 8.4 percent in the first three months of the year, while car loans to borrowers with high credit scores slipped 2.5 percent, according to Experian Automotive. Subprime auto loans accounted for 35.4 percent of the $726 billion in outstanding car loans in the first quarter. That is shy of 2009, when such loans comprised nearly 40 percent of the market, but an indication that the market is roaring back. And that worries consumer groups.