In an effort to boost slumping auto sales, GMAC, the financing arm of General Motors ( GM - Get Report), says it will resume lending to subprime borrowers and reduce some dealer fees.

"We want to do our part to support both the U.S. auto industry and individuals in the market for a car or truck," said GMAC President Bill Muir, in a prepared statement. "GMAC now finances a broad spectrum of auto buyers, similar to traditional levels."

For retail customers, GMAC said it would accept applications from customers with credit bureau scores below 620, increase allowable advance rates and reduce some financing rates.

"Over the next 60 days, GMAC will make available at least $5 billion in order to increase the flow of credit to U.S. automotive customers, Muir said. Through March, GMAC financed over $2 billion in auto contracts.

For dealers, GMAC said that during April, it will eliminate curtailment payments, which are required after has remained in inventory for an extended payments. Through June, it will waive the fee for dealers to post aged vehicles on SmartAuction, GMAC's leading online marketing site. It will also allow qualified dealers the option to defer wholesale interest charges for two 30-day periods during the next 120 days.