WOLFSBURG, Germany — German carmaker Volkswagen capped two grim days for the country’s auto industry by revealing its diesel emissions cheating cost it a chunky 16.2 billion euros ($18.2 billion) for 2015 alone — and that’s likely only a part of the total bill.The revelation last September from U.S. environmental authorities that the company had been cheating on emissions test rocked one of the most venerable brand names in the auto industry and cost it its chief executive as well as a host of …