(2) (A) In this paragraph, “electric vehicle” means a vehicle powered primarily by an electric motor drawing electrical current from a portable source. (B) If a manufacturer manufactures an electric vehicle, the Administrator shall include in the calculation of average fuel economy under paragraph (1) of this subsection equivalent petroleum based fuel economy values determined by the Secretary of Energy for various classes of electric vehicles. The Secretary shall review those values each year and determine and propose necessary revisions based on the following factors: (i) the approximate electrical energy efficiency of the vehicle, considering the kind of vehicle and the mission and weight of the vehicle. (ii) the national average electrical generation and transmission efficiencies. (iii) the need of the United States to conserve all forms of energy and the relative scarcity and value to the United States of all fuel used to generate electricity. (iv) the specific patterns of use of electric vehicles compared to petroleum-fueled vehicles.