((a)) ** .—** In this section, “executive agency” has the same meaning given that term in .

((b)) ** .—**

((1)) The President shall prescribe regulations that require passenger automobiles leased for at least 60 consecutive days or bought by executive agencies in a fiscal year to achieve a fleet average fuel economy (determined under paragraph (2) of this subsection) for that year of at least the greater of—

((A)) 18 miles a gallon; or

((B)) the applicable average fuel economy standard under section 32902(b) or (c) of this title for the model year that includes January 1 of that fiscal year.

((2)) Fleet average fuel economy is—

((A)) the total number of passenger automobiles leased for at least 60 consecutive days or bought by executive agencies in a fiscal year (except automobiles designed for combat-related missions, law enforcement work, or emergency rescue work); divided by

((B)) the sum of the fractions obtained by dividing the number of automobiles of each model leased or bought by the fuel economy of that model.