Diesel fuel means any fuel sold in any State or Territory of the United States and suitable for use in diesel engines, and that is one of the following:
(1) A distillate fuel commonly or commercially known or sold as No. 1 diesel fuel or No. 2 diesel fuel;
(2) A non-distillate fuel other than residual fuel with comparable physical and chemical properties (e.g., biodiesel fuel); or
(3) A mixture of fuels meeting the criteria of paragraphs (1) and (2) of this definition.
40 CFR § 80.2
Definitions apply in this part as described in this section.