N.C. Gen. Stat. § 136-28.15: Diesel vehicles purchase warranty requirement.

Every new motor vehicle transferred to or purchased by the Department of Transportation that is designed to operate on diesel fuel shall be covered by an express manufacturer's warranty that allows the use of B-20 fuel, as defined in G.S. 143-58.4. This section does not apply if the intended use, as determined by the Department, of the new motor vehicle requires a type of vehicle for which an express manufacturer's warranty allows the use of B-20 fuel is not available. (2007-420, s. 3.)