California Air Resources Board

In 2002, the Board adopted California Interim Certification Procedures for 2004 and Subsequent Model Hybrid-Electric Vehicles in the Urban Bus and Heavy-Duty Vehicle Classes (interim procedure). This interim procedure was adopted in conjunction with modifications to the Public Transit Bus Fleet Rule to reflect advances in technology that could not be captured in ARB’s existing heavy-duty certification procedures.

Manufacturers must follow ARB's Heavy-Duty Certification Requirements in order to legally sell heavy-duty engines in California. The interim procedure is designed for heavy-duty hybrid-electric vehicle manufacturers seeking voluntary vehicle-based (as opposed to engine-based) certification. The interim procedure is based on a modified version of the Society of Automotive Engineers (SAE) Recommended Practice SAE J2711. This protocol was developed to test the emissions of heavy-duty hybrid-electric vehicles using a chassis dynamometer.  The ARB certification value for a heavy-duty hybrid-electric vehicle is determined through calculations using chassis dynamometer test results and engine certification values for both the hybrid-electric vehicle and a comparable conventional drivetrain vehicle.

In 2014, the Board adopted the amendments to the California Interim Certification Procedures for 2004 and Subsequent Model Hybrid-Electric and Other Hybrid Vehicles in the Urban Bus and Heavy-Duty Vehicle Classes. The amendments expand the applicability of the certification procedures to allow more vocational vehicles, such as beverage, package, and linen delivery vehicles, to certify. Additionally, the amendments are to clarify and enhance certification requirements, including updates to definitions and test procedures. The amended interim procedures remain voluntary, and their formal regulatory documents are posted on the Heavy-Duty GHG Phase 1 2013 webpage.

Updates:

Due to expanding commercialization and advancement of hybrid technology into more sectors of the heavy-duty market, the need to better quantify emission reductions from existing and future heavy-duty hybrid vehicles, and the fact that the current interim hybrid certification procedures have not been embraced or utilized by manufacturers, staff believes that updates to the existing powertrain testing provisions are warranted.

CARB staff is therefore working on amendments to the Phase 2 GHG emission standards that would allow heavy-duty hybrid vehicle manufacturers to seek voluntary powertrain-based (as opposed to engine-based, or chassis dynamometer-based) certification.  The proposed amendments to the powertrain procedures are based on U.S. EPA Phase 2 GHG technical amendments for powertrain testing.  More information concerning these amendments is on Heavy-Duty Low NOx website.