(a) Exercise of President’s authority pursuant to executive order respecting use 
The President shall, by executive order, require that motor vehicles which are owned or leased by Federal agencies and are capable of operating on gasohol shall use gasohol where available at reasonable prices and in reasonable quantities.

(b) Exceptions 
The President may provide for exceptions to the requirement of subsection (a) of this section where necessary, including to protect the national security.

(c) Gasohol requirements 
Such executive order shall specify the alcohol-gasoline mixture or mixtures which shall constitute gasohol for purposes of such order, as well as specifications for its use.