EPA GHG Rule Changes: Why CFR Part 1065/1066 Testing Still Matters
EPA regulations for greenhouse gas (GHG) emissions from vehicles and engines are shifting this year following the final ruling in February. At first glance, it may seem like testing requirements would decrease. But that’s not what we’re seeing. Instead:
- OEMs are doubling down on defensible data validation
- State regulations remain active
- Global GHG measurement requirements haven’t changed (EU, China, etc.)
- Advanced powertrain efficiency work remains CO₂-driven
The rescission of federal greenhouse gas (GHG) standards has raised important questions across the industry. Manufacturers are asking what testing is required and where they should focus their efforts.
Here’s the reality.
Criteria pollutants remain fully regulated and enforceable. They have been regulated since the 1970s and remain mandatory for OEMs to control and comply with current standards. Requirements for CO, NOx, THC, NMOG, and PM in vehicle tailpipe exhaust—as well as evaporative emissions (hydrocarbons from fuel vapor)—continue to demand rigorous in-use compliance. These are not going away—and neither is the complexity involved in measuring them accurately.
At the same time, OEMs no longer need to report or comply with certain greenhouse gas (GHG) requirements. However, they still need to measure CO₂. CO₂ measurement plays a critical role in determining vehicle exhaust volume. Testing laboratories use exhaust volume to calculate mass-based emissions for criteria pollutants under established CFR testing procedures (40 CFR Part 1065 and 1066). Less regulation does not mean less measurement.
The scientific community needs support now more than ever to advance research on rulemaking, particularly in light of the uncertainty created by the Loper Bright Enterprises v. Raimondo decision regarding the validity of agency regulations. Research institutions, universities, OEMs, suppliers, and testing services must continue to collaborate to mitigate the well-documented negative effects of motor vehicle exhaust on public health.
As regulations continue to evolve, maintaining accurate emissions of data remains essential for industry stakeholders. TRP Laboratories remains fully equipped to support GHG-related measurement and quantification, not only for CO₂, but also N₂O and CH₄ and continues to offer testing services aligned with GHG-specific procedures.
How Manufacturers & OEMs Should Respond
To stay competitive and prepared, companies should:
- Maintain CFR Part 1065/1066-compliant testing capabilities
- Expand support for CARB and state-level requirements
- Integrate emissions testing into broader validation programs
- Leverage independent labs for pre-compliance and risk reduction
What Manufacturers & OEMs Need to Consider
- GHG reporting requirements have been reduced, but CO₂ measurement remains necessary, as it is a fundamental component for determining vehicle exhaust volume. Without exhaust volume, mass-based values for criteria pollutants cannot be calculated using established CFR procedures.
- It’s not about checking a regulatory box. Compliance isn’t the only driver—it’s about protecting timelines, avoiding rework, and making engineering decisions backed by credible data.
Why Independent Testing Matters More Than Ever
As federal oversight shifts and courts take a more active role in interpreting regulatory authority, independent testing laboratories become even more critical in:
- Providing objective, defensible emissions data
- Supporting flexible and adaptive testing programs
- Accelerating time to market
- Ensuring readiness across multiple regulatory pathways
Manufacturers and OEMs that will lead are those that recognize the importance of high-quality datasets in reducing risk across vehicle test programs. While regulatory frameworks continue to evolve, one thing remains constant: the need for reliable, defensible emissions data.