Section 86.1301 - Scope; applicability(a) This subpart specifies gaseous emission test procedures for Otto-cycle and diesel heavy-duty engines, and particulate emission test procedures for diesel heavy-duty engines.(b) You may optionally demonstrate compliance with the emission standards of this part by testing hybrid engines and hybrid powertrains using the test procedures in 40 CFR part 1036, rather than testing the engine alone. If you choose this option, you may meet the supplemental emission test (SET) requirements by using the SET duty cycle specified in either § 86.1362 or 40 CFR 1036.510 . Except as specified, provisions of this subpart and subpart A of this part that reference engines apply equally to hybrid engines and hybrid powertrains.(c) The abbreviations and acronyms from subpart A of this part apply to this subpart. 88 FR 4475 , Jan. 24, 2023 81 FR 73981 , 12/27/2016; 88 FR 4475 , 3/27/2023