Hold on to your wallet. Last December Congress mandated higher CAFE standards, 35 mpg by 2020. Detroit automakers, already under assault from import competitors and slower economic growth, cried foul. They claimed billions of dollars would be needed to retool their plants to meet the standard. Congress provided $25 billion in low cost loans to help the automakers. Now with the presidential election looming and Ohio and Michigan must-win states, automakers are seeking an additional $25 billion.