Rulemaking- Chapter 173-423 WAC Clean Vehicles Program Rulemaking: Formal Comment Period
Ecology is proposing revisions to chapter 173-423 WAC, Washington’s Clean Vehicles Program rule. These revisions align with California’s changes to vehicle emissions standards that apply to new passenger and commercial vehicles sold in Washington. Vehicle emissions standards are an essential policy tool for addressing climate change and reducing harmful air pollution from vehicles, particularly in communities most exposed to this type of pollution. This rulemaking creates a path for reinstating older standards if current standards become unenforceable due to recent federal actions. Washington holds these recent federal actions as unlawful, and litigation is ongoing. The older standards that this rulemaking would reinstate were phased out in favor of the current, more protective standards. However, they are still a safer and more effective fallback than the federal standards Washington would default to without these rule changes.
Ecology is proposing to adopt amendments to Advanced Clean Cars and Advanced Clean Cars II, both of which apply to light-duty passenger vehicles, pickup trucks, and medium-duty vehicles. Amendments would re-establish Advanced Clean Cars certification standards for combustion engine vehicles—which were replaced by Advanced Clean Cars II beginning in model year 2026—as a certification option for manufacturers. These certification standards ensure that new combustion engine vehicles sold in Washington pollute less.
Additionally, Ecology is proposing to adopt components of California’s 2010 medium- and heavy-duty vehicle in-use standards, which were replaced by Heavy-Duty Low NOx Omnibus. Similar to the light-duty standards above, the 2010 in-use regulation would act as a backstop emission standard for medium- and heavy-duty vehicles if the federal government succeeds in eliminating our ability to enforce Heavy-Duty Low NOx Omnibus.
California Regulations Proposed for Adoption by Reference:
The relevant sections that Ecology is considering adopting by reference from the California Code of Regulations are listed below.
o 95300.0.1 – 95307.0.1, 95311.0.1, 95660.0.1 – 95663.0.1
Ecology is also proposing additional fleet reporting requirements, beyond the one-time report required in 2023, to authorize additional data collection. This data would be used to support utility grid planning, the development of state-funded transportation electrification grant programs, and other efforts to reduce carbon emissions from transportation.
These rule revisions are important to streamline program implementation, provide additional compliance flexibility and clarity, maintain consistency with other states and the federal government, and work toward meeting Washington’s limits on greenhouse gas emissions.
To read the proposed rule language and learn more about this rulemaking, visit our rulemaking webpage
Next Steps:
After the close of the comment period, Ecology will review and respond to comments. We will send out a notice about the next steps to anyone who provided contact information.
Contact Information
*Indicates Required Fields
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Ecology is proposing revisions to chapter 173-423 WAC, Washington’s Clean Vehicles Program rule. These revisions align with California’s changes to vehicle emissions standards that apply to new passenger and commercial vehicles sold in Washington. Vehicle emissions standards are an essential policy tool for addressing climate change and reducing harmful air pollution from vehicles, particularly in communities most exposed to this type of pollution. This rulemaking creates a path for reinstating older standards if current standards become unenforceable due to recent federal actions. Washington holds these recent federal actions as unlawful, and litigation is ongoing. The older standards that this rulemaking would reinstate were phased out in favor of the current, more protective standards. However, they are still a safer and more effective fallback than the federal standards Washington would default to without these rule changes.
Ecology is proposing to adopt amendments to Advanced Clean Cars and Advanced Clean Cars II, both of which apply to light-duty passenger vehicles, pickup trucks, and medium-duty vehicles. Amendments would re-establish Advanced Clean Cars certification standards for combustion engine vehicles—which were replaced by Advanced Clean Cars II beginning in model year 2026—as a certification option for manufacturers. These certification standards ensure that new combustion engine vehicles sold in Washington pollute less.
Additionally, Ecology is proposing to adopt components of California’s 2010 medium- and heavy-duty vehicle in-use standards, which were replaced by Heavy-Duty Low NOx Omnibus. Similar to the light-duty standards above, the 2010 in-use regulation would act as a backstop emission standard for medium- and heavy-duty vehicles if the federal government succeeds in eliminating our ability to enforce Heavy-Duty Low NOx Omnibus.
California Regulations Proposed for Adoption by Reference:
The relevant sections that Ecology is considering adopting by reference from the California Code of Regulations are listed below.
Revising Existing Sections:
· California Code of Regulations, Title 13
o 1900, 1956.8, 1961.2 – 1961.4, 1962.2 – 1962.4, 1965, 1968.2, 1968.5, 1969, 1971.1, 1971.5, 1976, 1978, 2035 – 2
038, 2040, 2111 – 2119, 2121, 2123, 2125 – 2131, 2137, 2139 – 2149 (including
2139.5), 2166, 2166.1, 2167, 2168, 2169, 2169.1- 2169.8, 2170, 2423, 2485
· California Code of Regulations, Title 17
o 95300 – 95307, 95311, 95660 – 95663
New Sections:
· California Code of Regulations, Title 13
1900.0.1, 1956.8.1, 1956.8.2, 1961.2.1, 1962.2.1, 1962.3.1, 1965.0.1, 1968.2.1, 1968.5.1, 1969.0.1, 1971.1.1, 1971.5.1, 1976.0.1, 197
8.0.1, 2035.0.1 – 2040.0.1, 2111.0.1 – 2119.0.1, 2121.0.1, 2123.0.1, 2125.0.1 – 2131.0.1,
2137.0.1, 2139.0.1 – 2149.0.1, 2317.0.1, 2423.0.1, 2485.0.1
· California Code of Regulations, Title 17
o 95300.0.1 – 95307.0.1, 95311.0.1, 95660.0.1 – 95663.0.1
Ecology is also proposing additional fleet reporting requirements, beyond the one-time report required in 2023, to authorize additional data collection. This data would be used to support utility grid planning, the development of state-funded transportation electrification grant programs, and other efforts to reduce carbon emissions from transportation.
These rule revisions are important to streamline program implementation, provide additional compliance flexibility and clarity, maintain consistency with other states and the federal government, and work toward meeting Washington’s limits on greenhouse gas emissions.
To read the proposed rule language and learn more about this rulemaking, visit our rulemaking webpage
Next Steps:
After the close of the comment period, Ecology will review and respond to comments. We will send out a notice about the next steps to anyone who provided contact information.
Contact Information
*Indicates Required Fields