In biofuels: vehicles/engines that use alternative fuels such as biodiesel, bioethanol, natural gas, electricity, hydrogen, and automotive LPG, instead of gasoline and diesel [Section 3(b), Biofuels Act of 2006; Section 3.1(c), DOE Department Circular No. DC2007-05-0006, Rules and Regulations Implementing Republic Act No. 9367]
