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EPA adds new research to Phase 2 GHG proposal

EPA adds new research to Phase 2 GHG proposal

Agency calls for comment on powertrain, aero reports

The federal government has come up with new information related to the next round of fuel efficiency and greenhouse gas emissions standards for heavy-duty trucks, and the agencies behind the proposal are calling for another round of public comment on the latest additions to the rulemaking docket.

According to the notice published Wednesday in the Federal Register, the Environmental Protection Agency (EPA) and the National Highway Traffic Safety Administration (NHTSA) are soliciting additional comment on “certain revised test reports," and a revised version of the Greenhouse Gas Emission Model (GEM) used in developing the proposed standards.

The new information includes powertrain data; additional aerodynamic test data; supplemental test data relating to drive cycles for vocational vehicles; and cycle average mapping data.

The agencies proposed the Phase 2 Heavy-Duty National Program last July, and the original public comment period closed Oct. 1. The current period runs through April 1, and the Wednesday notice emphasizes that the agencies will not address “new comments extraneous to these materials.”

In an update on the GHG proposal, Stemco’s Fritz Marinko told attendees at the Technology & Maintenance Council’s annual meeting this week the rule is slated to be finalized this summer, “but in reality it could be extended.”

Also uncertain is the extent to which the final rule will accede to the more stringent standards and a more aggressive implementation schedule sought by the California Air Resources Board (CARB). Specifically, CARB wants the rule to push for more advanced technologies, to address aerodynamics in vocational vehicles, and “knowing CARB, they’re always concerned about NOx,” Marinko explained. And all this by 2024, rather than 2027 timetable sought by the trucking industry.

“CARB has publicly stated that they’re very committed to single, strong program,” Marinko said. “But the reality is if they don’t like what written, they’re going to write their own. Six to twelve months after the federal regulation becomes law, they will come with their own regulation. They’re going to do their own thing, no matter what the federal regulation is.”

To review or to comment on “Greenhouse Gas Emissions and Fuel Efficiency Standards for Medium- and Heavy-Duty Engines and Vehicles - Phase 2,” go here on

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