On July 5, EPA announced that a nationally recognized, independent testing laboratory is able to certify compliance by underground storage tank owners and operators with rules for storing ethanol and biodiesel blends. This new guidance applies to tanks and UST system components containing gasoline with more than 10% ethanol or diesel containing more than 20% biodiesel. The final guidance came the same day Rep. F. James Sensenbrenner (R-WI) told the EPA in a letter that automakers are afraid that ethanol blends of greater than 10 percent will damage the engines of newer vehicles, reduce fuel efficiency, and possibly void warranties.