Directs the EPA Administrator to finalize a proposed rule on E15 fuel labeling and underground storage tank (UST) compatibility within 90 days of enactment. It requires adoption of labeling and compatibility provisions for fuel blends up to 15% ethanol, mandates that any newly installed or replacement UST components be compatible with fuel blends up to 100% ethanol, and protects existing tank systems from being deemed noncompliant solely because owners lack historical installation or compatibility documentation.