. (c) Effective dates (1) Extension of credit The amendment made by subsection (a) shall apply to property placed in service after December 31, 2017. (2) Modification of dollar limitation The amendment made by subsection (b) shall apply to taxable years beginning after December 31, 2017. 6. Liquefied natural gas equivalent for purposes of Inland Waterways Trust Fund financing rate (a) In general Section 4042(b)(2)(A) of the Internal Revenue Code of 1986 is amended to read as follows: (A) The Inland Waterways Trust Fund financing rate is 29 cents per gallon (per energy equivalent of a gallon of diesel, in the case of liquefied natural gas). . (b) Energy equivalent of a gallon of diesel Section 4042(b) of the Internal Revenue Code of 1986 is amended by adding at the end the following: (5) Energy equivalent of a gallon of diesel with respect to liquefied natural gas For purposes of paragraph (2)(A), the term energy equivalent of a gallon of diesel means 6.06 pounds of liquefied natural gas. . (c) Effective date The amendments made by this section shall apply to any sale or use of fuel after December 31, 2018. 7. Federal acquisition of alternative fueled vehicles (a) Acquisition of natural gas vehicles by General Services Administration (1) In general Not later than 180 days after the date of the enactment of this Act, in order to increase the acquisition of natural gas vehicles, the Administrator of General Services shall— (A) review statutory requirements and regulations for impediments against the acquisition of natural gas vehicles