The Environmental Protection Agency and the National Highway Traffic Safety Administration have officially published the Phase 2 greenhouse gas/ fuel efficiency rule for commercial vehicles in the Federal Register.

The rule was finalized in August and now that it has been published it in the Federal Register, it has an effective date of December 27, 2016.

In more than 2,000 pages, the GHG Phase 2 rule sets new standards for commercial vehicle and trailer manufacturers to further reduce greenhouse gas emissions and increase fuel economy goals. It expands on the GHG Phase 1 goals and is aimed at creating a cleaner and more efficient generation of commercial vehicles through existing technologies and new innovations.

The rule sets CO2 limits for Model Year 2021 to 2027 trucks and tractors and Model Year 2018 to 2027 trailers as entire vehicles. The rule also sets separate engine fuel-efficiency standards for each category of commercial vehicle, including light-, medium- and heavy-duty vehicles. Also, for the first time, the GHG Phase 2 rule will regulate trailers.

Taken as a whole, the rule requires engine manufacturers to reduce CO2 emissions by 4%-5% from 2017 through 2027 and to attain fuel efficiency improvements of 16% or better for vocational and heavy-duty vehicles.

GHG Phase 2 also includes rules for natural gas vehicles and engines to reduce methane emissions and regulates glider kits, requiring engines to meet the same standards as new vehicles.