Volkswagen AG has agreed to a $1 billion settlement to fix or buy back another 80,000 polluting diesel vehicles sold in the United States as the German automaker took new steps to put its emissions cheating scandal behind it. The settlement deal covered luxury VW, Audi and Porsche vehicles with 3.0-liter engines, meaning Volkswagen has now agreed to spend as much as $17.5 billion in the United States to resolve claims from owners as well as federal and state regulators over polluting diesel vehicles. The world's No. 2 automaker still faces the possibility of spending billions of dollars more to resolve a U.S. Justice Department criminal investigation and federal and state environmental claims, as well as oversight by a federal monitor.