NEW YORK (Standard&Poor's) Sept. 16, 2015--Standard&Poor's Ratings Services said today that it assigned its 'BBB-' issue-level rating to Fort Lauderdale, Fla.-based auto retailer AutoNation Inc.'s proposed $750 million senior unsecured notes, $300 million of which will mature in 2021 and $450 million in 2025. The company states it will use the proceeds to reduce borrowings under its revolving credit facility. In our view, the debt issuance will have no significant impact on the company's financial metrics; moreover, its financial flexibility will be improved by increasing availability under its revolver and extending the duration of maturities. The proposed senior notes will rank equally with all existing and future senior unsecured debt and will be senior to all