Much as I hate to agree with His RINOness King George about anything, he's right on the money with this one.
Right now, we could replace 5 percent of petroleum diesel with biodiesel, and five percent of petroleum gasoline with ethanol without any vehicle damage or modifications.
Higher percentages of either require vehicle modifications but are very doable.
But would folks here at FR be willing to increase the nation's fuel supply by five percent without building any more petroleum refineries or importing any more oil?
A note: Adding 5% biodiesel to the new "cleaner" Ultra Low Sulfur Diesel (ULSD) further improves emissions and makes the fuel easier on the engine due to improved lubricity (ULSD doesn't lubricate well.)