Several passenger vehicles come with a flex-fuel option that allows them to run on ethanol/gasoline blends from 0 percent to 85 percent ethanol. Even normal gasoline vehicles can operate on a 10 percent ethanol blend with no problems. Diesel cars and trucks can run on biodiesel, though older models may need to have their fuel lines and gaskets replaced with modern synthetic materials, since biodiesel is a solvent (see References 1). Some diesel owners have also modified their vehicles to run on straight vegetable oil.
Recent testing has shown the viability of biofuel use in the aviation industry, and use of biofuels to power aircraft is expected to increase substantially in the next decade. Because current biofuel production relies heavily on crops that also function as food or livestock feed, emphasis is on developing new sources that don't cause deforestation and compete with food production. A plant called camelina --- part of the mustard family --- shows early promise.