- SUBPART A - Subpart A—Overview and Applicability
- SUBPART B - Subpart B—Emission Standards and Related Requirements
- SUBPART C - Subpart C—Certifying Vehicle Families
- SUBPART D - Subpart D—Testing Production Vehicles and Engines
- SUBPART E - Subpart E—In-Use Testing
- SUBPART F - Subpart F—Test and Modeling Procedures
- SUBPART G - Subpart G—Special Compliance Provisions
- SUBPART H - Subpart H—Averaging, Banking, and Trading for Certification
- SUBPART I - Subpart I—Definitions and Other Reference Information