; or (II) any other method deemed acceptable to the Administrator. (E) Regulations (i) In general The Administrator shall promulgate regulations to implement this paragraph. (ii) Contents Regulations promulgated under clause (i) shall allow for the generation of tradeable credits to meet the requirement of subparagraph (A), but any credits shall expire after not more than 5 years. (iii) Initial regulations Not later than January 1, 2027, the Administrator shall promulgate final regulations under clause (i). (3) Low-carbon octane (A) Prohibition Effective beginning on January 1, 2027, no refiner or importer shall introduce into commerce motor vehicle gasoline with a research octane number of 95 or higher except through the use of a fuel additive that has average lifecycle greenhouse gas emissions that (as determined by the Secretary of Energy using the most recent version of the Argonne National Laboratory Greenhouse gases, Regulated Emissions, and Energy use in Technologies (GREET) model) are at least 40 percent less than baseline lifecycle greenhouse gas emissions. (B) Regulations (i) In general The Administrator shall promulgate regulations to implement this paragraph. (ii) Contents Regulations promulgated under clause (i) shall— (I) determine the baseline lifecycle greenhouse gas emissions for purposes of this paragraph; (II) determine the average lifecycle greenhouse gas emissions of sources of octane value for purposes of this paragraph