The fuel industry's American Petroleum Institute tested the 15 percent ethanol gas approved in 2010 and found it gums up fuel systems, prompts "check engine" lights to come on, and messes with fuel gauge readings. "Failure of these components could result in breakdowns that leave consumers stranded on busy roads and highways," said the industry report. Worse: API said the fuel problems--not found in E5 or E10 blends--aren't always covered by auto warranties. The industry prefers pure fuel to an ethanol mix, but the report isn't likely to slow the administrations green push