EPA proposed changes to the test procedures used for heavy-duty engines and vehicles to demonstrate compliance with emission standards. These changes improve accuracy and reduce testing burden. EPA also proposed other regulatory amendments concerning light-duty vehicles, heavy-duty vehicles, highway motorcycles, locomotives, marine engines, other nonroad engines and vehicles, stationary engines, and portable fuel containers. If finalized, these other regulatory amendments would streamline the regulations which would reduce industry costs, increase compliance flexibility, harmonize with other requirements, clarify existing requirements, and correct errors.