U.S. Commercial Truck Retirement and Scrappage

Key findings

Sources: FHWA Highway Statistics 2024, Table VM-1; BTS VIUS Summary Statistics Report; EPA MOVES6 technical reports. Registration and VMT figures are FHWA published estimates; percentages are arithmetic from those totals, not physical scrappage rates.

What does truck retirement actually mean?

The word retirement is used differently in fleet management, vehicle-registration analysis, and dismantling. A fleet manager might retire a Class 8 tractor when it no longer meets a long-haul operating requirement. The vehicle could be sold to a regional carrier, reassigned to shorter routes, or purchased for parts.

For the original fleet, retirement has occurred. For the truck itself, continued service may still be possible. An owner with an aging box truck, dump truck, or service truck faces a similar distinction: the equipment may no longer suit the owner’s business without having reached the end of its physical life.

Definitions that should not be confused

A surviving truck may have passed through multiple owners. Conversely, a vehicle absent from one dataset may still exist and operate elsewhere.

For this article, physical scrappage means permanent removal of the vehicle from potential service through dismantling, disabling, or destruction. A fleet sale or deregistration does not meet that definition by itself.

Which commercial trucks are included in the data?

Commercial trucks are commonly grouped by gross vehicle weight rating (GVWR), the manufacturer’s maximum rated loaded vehicle weight. Classes 3-6 are generally medium-duty trucks, while Classes 7-8 are heavy-duty trucks.

Reference: U.S. Department of Energy, Alternative Fuels Data Center vehicle-class resources. Weight class does not dictate body style or commercial use.

Classes 1 and 2 include many pickups, SUVs, and other lighter vehicles. Some are used commercially, but they should not be silently mixed into claims about medium- and heavy-duty vehicles.

Why FHWA categories are different

FHWA’s Table VM-1 uses categories such as single-unit trucks and combination trucks. Its single-unit category covers single-frame trucks with two axles and at least six tires, or vehicles with GVWR above 10,000 pounds. Combination trucks are reported separately.

These definitions are not equivalent to a complete VIN-level census of Classes 3-8 by actual business use. Different systems may classify a truck by GVWR, configuration, manufacturer type, or emissions-model source type.

A tractor designed to haul a trailer is not identical to a completed straight truck with a cargo body attached. Analysts should not treat them as interchangeable merely because both are commercial trucks.

U.S. truck registrations and vehicle miles traveled

FHWA’s Highway Statistics 2024 edition provides a consistent presentation of national 2023 and 2024 truck-category totals. These figures combine state-related reporting and FHWA estimation procedures. They are useful for studying population and activity, but they are not an individual-truck history showing entries and final exits.

FHWA national truck figures, 2023 and 2024

Source: FHWA Highway Statistics 2024, Table VM-1, updated February 2026. Both years come from this one edition, not mixed revisions. VMT means vehicle miles traveled; the totals above are expressed in millions of miles.

FHWA’s published 2023 combined VMT is 329,858 million miles. Adding its separately rounded component values gives 329,859 million miles. This one-million-mile difference arises from rounding, so the calculations here use the published combined figure.

Original calculation 1: Reported registration change

For 2023: 11,567,428 + 3,324,112 = 14,891,540.

For 2024: 12,599,614 + 3,482,896 = 16,082,510.

Absolute difference = 16,082,510 – 14,891,540 = 1,190,970 registrations.

Percentage difference = (1,190,970 / 14,891,540) x 100 = approximately +8.0%.

This measures the change in the published registration population, not new truck manufacturing, truck purchases, or trucks physically retired.

FHWA’s separate 2024 Table MV-1 notes that New York moved from estimated registration figures for 2022 and 2023 to actual state-reported figures in 2024. That reporting change is a reason to be careful with year-over-year registration comparisons. It does not establish how much of the national VM-1 change New York’s revised reporting caused.

Reporting note: FHWA State Motor-Vehicle Registrations, Table MV-1.

Original calculation 2: Change in reported road mileage

The published combined FHWA totals were 329,858 million vehicle-miles in 2023 and 329,600 million in 2024.

Difference = 329,600 – 329,858 = -258 million vehicle-miles.

Percentage change = (-258 / 329,858) x 100 = approximately -0.08%.

Reported mileage therefore remained nearly unchanged despite the published registration increase. FHWA’s combined average annual mileage per registered truck declined from 22,151 to 20,494 miles, approximately 7.5%.

This does not prove that every truck was driven less, that more vehicles entered storage, or that scrappage changed. A population average can shift because of vehicle composition, economic conditions, reporting methodology, estimated activity, and other factors.

Original calculation 3: Different truck groups account for different activity

In 2024, combination trucks represented the following share of the two-category registration total:

3,482,896 / 16,082,510 x 100 = approximately 21.7%.

Their share of combined truck VMT was:

192,520 / 329,600 x 100 = approximately 58.4%.

FHWA also reports average mileage of 55,276 annual miles for a combination truck and 10,880 for a single-unit truck in 2024. The combination-truck average was approximately 5.1 times the single-unit average.

That does not show which group has a longer physical lifespan. It shows that the categories have markedly different reported road-use patterns. Using one mileage threshold or uniform retirement assumption for all commercial trucks would hide those differences.

What does the 2021 Vehicle Inventory and Use Survey reveal?

The U.S. Census Bureau conducts the Vehicle Inventory and Use Survey (VIUS) in partnership with federal transportation and energy agencies. The latest completed VIUS data identified in this review concern 2021 vehicle characteristics and activity, collected in 2022. A Bureau of Transportation Statistics (BTS) summary was published on January 22, 2026.

The survey sampled approximately 150,000 vehicles and received almost 68,000 completed questionnaires. It includes personal and commercially used trucks across Classes 1-8, including pickups, minivans, SUVs, straight trucks, and truck tractors.

Why the survey population matters

The VIUS sample excludes government-owned vehicles, buses, ambulances, fire engines, motor homes, certain nonroad equipment, trailers, and other out-of-scope vehicles. New Hampshire was excluded from the main 2021 survey because the state did not provide access to its vehicle-registration records. Census separately released experimental national estimates incorporating modeled New Hampshire data.

The standard VIUS estimates should therefore not be treated as an exhaustive national census of every commercial vehicle in service.

Sources: Census VIUS scope and design and Census experimental New Hampshire estimates.

Truck tractors and other heavy trucks do different work

Source: BTS VIUS Summary Statistics Report, January 22, 2026. These are rounded sample-based estimates for 2021, not 2026 truck counts or physical-retirement totals. They do not match FHWA’s VM-1 categories one-for-one.

A long-distance tractor may accumulate considerable highway mileage while a vocational truck may accumulate fewer road miles but substantial engine or auxiliary operating hours. Concrete mixers, septic pumping trucks, dump trucks, and utility vehicles may experience wear related to load cycles, pumping equipment, hydraulic systems, corrosion, or other application-specific conditions. Road mileage does not describe every source of wear.

Truck age is not the same as truck lifespan

VIUS provides information about model years and vehicle use. It can describe the ages of vehicles in the sampled population, but a cross-sectional age distribution cannot determine when each truck will ultimately be scrapped.

A 20-year-old vehicle in a survey demonstrates survival within the relevant survey population at that age. It does not identify the truck’s future retirement date. Similarly, the mean age of operating trucks is not the mean lifetime at final destruction of all trucks originally manufactured.

A comprehensive survival study would follow compatible vehicle cohorts, account for vehicles leaving the reporting population, and distinguish destruction from other exits. No new survey-weighted national Classes 3-8 age distribution or cohort-survival model was calculated for this article.

What academic research reveals about data compatibility

A peer-reviewed study published in the International Journal of Sustainable Transportation in December 2025 compared commercial fleet composition estimated from the 2021 VIUS with EPA MOVES4 model defaults.

Within the researchers’ defined medium- and heavy-duty grouping, the VIUS-derived population was approximately 45% lower, and the vehicle-mileage estimate approximately 36% lower, than the corresponding MOVES4 values. These differences concern that study’s survey-derived and modeled populations, not annual physical retirements or scrappage rates.

The comparison illustrates the need to reconcile source definitions, age structures, and activity assumptions before comparing two truck populations.

Research: Improving Commercial Truck Fleet Composition in Emission Modeling Using 2021 US VIUS Data (2025).

How long do commercial trucks last?

A universal commercial-truck lifespan is not supported by the evidence reviewed here. The answer depends on the vehicle, duty cycle, maintenance condition, operating environment, and the event used to define the end of life.

A vehicle can remain physically usable after its economic life ends for one operator. It can also move into a different duty cycle and continue serving another owner.

Mileage, operating hours, and condition

Commercial trucks experience different stresses. A highway tractor may accumulate substantial mileage in steady-speed travel. A local delivery truck may experience frequent stops. A refuse truck may cycle hydraulic systems repeatedly, while a specialized vocational truck may spend considerable time running stationary equipment.

Vehicle condition is shaped by maintenance, payload demands, road and weather exposure, corrosion, repairs, and parts availability. Age and odometer reading should be evaluation inputs, not standalone judgments about scrappage. No unsupported average lifespan is assigned here to semi trucks, box trucks, dump trucks, concrete mixers, or other categories.

Historical heavy-truck survival estimates versus current models

Oak Ridge National Laboratory’s Transportation Energy Data Book, Edition 40, includes historical heavy-truck survival and scrappage modeling for model-year cohorts including 1970, 1980, and 1990. The material concerns trucks above 26,000 pounds gross vehicle weight and contains estimates under specified assumptions.

These curves help explain fleet-survival methods. They should not be presented as observations of 2026 truck destruction rates.

Source: ORNL Transportation Energy Data Book, Edition 40 (2022).

What EPA MOVES6 actually does

EPA’s MOVES6 emissions model was initially released in September 2026. The technical report Population and Activity of Onroad Vehicles in MOVES6, dated August 2026, describes the model’s population and age-distribution inputs.

Its appendix explains that limited heavy-duty scrappage evidence led EPA to use an ORNL 1980 model-year heavy-truck survival curve for relevant historical model-development inputs. EPA did not choose the 1990 curve because it produced substantially higher modeled survival at older ages that the agency considered implausible for this use.

Separate medium-duty survival information was unavailable from that source, so the selected heavy-duty curve was applied to other modeled categories. EPA also extended its trend beyond the source curve’s original age range.

Importantly, the survival-rate values are not actively used to calculate age distributions during an individual MOVES run. They helped develop default national age distributions stored in the model database.

Sources: EPA MOVES6 technical reports; Population and Activity of Onroad Vehicles in MOVES6, EPA-420-R-26-010, Appendix C (August 2026).

Can annual commercial truck scrappage be calculated from public data?

A defensible national estimate would require more than a change in reported registrations. A consistently defined registered-vehicle population changes through entries, exits, reclassifications, and measurement adjustments.

Ending population = Starting population + Entries – Exits + Net classification and reporting adjustments.

Entries may include newly registered vehicles, used imports, and vehicles returning after a period without registration. Exits may include permanent destruction, exports, extended nonregistration, or reclassification outside the measured population.

Domestic resale can change ownership without changing the national fleet population, although registration timing and jurisdictional reporting can affect apparent totals. The unresolved task is identifying the physical events behind the recorded changes.

Why registration data alone are insufficient

When a registered truck no longer appears in a reporting population, the analyst may not know whether it was exported, dismantled, temporarily unregistered, reclassified, or affected by record matching. The vehicle’s absence is a population-record event, not proof of destruction.

Likewise, rising registrations do not isolate how many existing trucks were replaced, how many were added through expansion, or how many older units continued operating.

Why new-truck sales do not equal retirements

Retail sales describe new equipment entering a market, not a one-for-one relationship between each new purchase and an older truck physically scrapped. A carrier might expand without retiring a tractor, or buy a new truck while selling its predecessor to another operator.

The Bureau of Economic Analysis publishes a heavy-weight truck retail-sales series covering trucks above 14,000 pounds gross weight, available through FRED, series HTRUCKSNSA. That threshold excludes some Class 3 vehicles and is not identical to the complete Classes 3-8 population. Sales provide replacement-market context, not verified destruction totals.

Why export records require careful treatment

Used commercial trucks may leave the United States and continue operating in other markets. Official merchandise-export statistics can help identify recorded movement under vehicle and tractor commodity classifications.

Commodity codes, reporting units, new-versus-used distinctions, and coverage must be assessed before linking those movements to a registered-truck population. A truck exported from the United States should not be counted as physically scrapped merely because it disappears from U.S. registration records.

The U.S. International Trade Commission DataWeb provides official trade records, but no reconciled national used-commercial-truck export total was calculated for this article.

What would be required for a defensible estimate?

A physical-scrappage study needs a consistent population and observation period plus sufficiently reliable information on:

• New and previously unregistered entries.
• Used vehicles imported into the defined population.
• Permanent physical destruction events.
• Exports and other permanent exits from U.S. service.
• Vehicles reactivated after inactivity.
• Reclassifications, duplicate records, and administrative changes.
• Uncertainty from missing records and inconsistent vehicle definitions.

Ideally, verified vehicle identifiers or a validated longitudinal cohort system would distinguish these pathways. Any estimated components would need explicit assumptions and uncertainty ranges.

What influences a commercial fleet’s retirement decisions?

Truck retirement decisions are shaped by operating economics, equipment condition, business requirements, and regulation. The factors below can explain an individual fleet’s choices, but they do not independently quantify national physical scrappage.

Repair costs and reliability

An operator may replace a truck when expected repairs, downtime, and operating restrictions make continued service unattractive. A costly repair does not always justify replacement. The decision also depends on other vehicle systems, future workload, the cost of alternative equipment, and the risk of further problems.

Freight demand and utilization

A business reducing routes may sell working vehicles that have not exhausted their useful lives. A growing business may add vehicles without retiring comparable equipment. Changes in freight demand should not be interpreted as direct changes in national scrappage without suitable evidence.

Replacement costs and used-truck markets

Availability and acquisition costs influence whether an operator repairs an existing vehicle or acquires another. Resale opportunities can move equipment among large fleets, smaller carriers, contractors, and specialized operators. Those transfers are not physical destruction.

Mileage, maintenance, and specialized equipment

A low-mileage truck can require substantial repairs if it has accumulated stationary engine hours, repeated load cycles, corrosion, or difficult worksite exposure. A vocational body and its chassis or powertrain can have different remaining service lives. Evaluations should consider the complete asset, not only model year or odometer.

Business changes

Fleet consolidation, lost service contracts, equipment standardization, and changing operating territories can create surplus trucks regardless of their mechanical condition. A decision to sell does not automatically mean the truck should be scrapped.

How regulations and replacement incentives can affect fleet turnover

Regulations may influence whether a vehicle is suitable for a particular operation, but requirements depend on the engine, vehicle, jurisdiction, date, and compliance circumstances. An operating or registration requirement does not necessarily mean the truck must be physically destroyed.

Federal engine and vehicle emissions requirements

On February 12, 2026, EPA finalized a rule rescinding the 2009 greenhouse gas endangerment finding and repealing federal on-highway motor vehicle and engine greenhouse gas emission standards under that action. EPA distinguishes this greenhouse gas action from requirements governing traditional air pollutants.

Separately, EPA maintains rules addressing smog, soot, and other pollutants from commercial trucks and buses. In July 2026, the agency published proposed amendments to certain compliance provisions for model-year 2027 and later heavy-duty engines. A proposal is not a final adopted requirement.

The current status of a rule and its application should be checked for the specific vehicle and transaction.

Official rules: EPA February 2026 greenhouse gas final rule; EPA commercial-truck traditional air-pollution rules.

California Truck and Bus Regulation

California’s Truck and Bus Regulation covers certain diesel vehicles operating in the state, generally those with GVWR above 14,000 pounds, with specified exemptions and compliance options. CARB explains that, as of January 1, 2023, most affected vehicles needed a 2010 or newer compliant engine and emissions system under the regulation’s schedule.

Covered noncompliant vehicles may face California DMV registration restrictions. Such a restriction does not, by itself, establish that an affected truck was physically scrapped.

Source: California Air Resources Board, Truck and Bus Regulation. Specific applicability and exceptions must be checked.

Diesel Emissions Reduction Act programs

EPA’s Diesel Emissions Reduction Act (DERA) programs support eligible diesel-emissions reduction projects. The 2025-2026 State Program identifies qualifying medium- and heavy-duty highway-vehicle applications, including Class 5-8 vehicles, and other equipment categories.

Certain replacement projects require evidence that an old eligible vehicle or engine was permanently disabled or scrapped under the funding rules. This condition concerns the specific project and funding arrangement, not every aging truck in the United States.

Project records may document actual destruction in that defined funded group, but they cannot be assumed to represent a national scrappage census.

Source: EPA DERA State Grants and program documents.

Repair, resell, or scrap? A practical decision framework

For a truck owner or fleet manager, a useful decision begins with condition and intended work, not a general industry age estimate. The following framework compares potential lawful options without inventing a purchase price or repair budget.

A more useful economic comparison

A fleet manager can compare expected future costs of retaining equipment with those of replacing it. One conceptual framework is:

Expected retention cost = Future repairs + Routine maintenance + Downtime exposure + Operating costs + Compliance costs – Expected residual value.

The replacement option should consider purchase or financing costs, operating differences, suitability for the job, and eventual resale value. These are planning categories, not EasyTruckBuyer’s actual appraisal formula. Vehicle-specific information is necessary before inserting any dollar amounts.

For example, occasional-use equipment may justify a repair that would be unattractive for a truck needed continuously on a time-sensitive route. Safety, registration eligibility, insurance, and compliance remain important whatever the financial result.

Preparing an aging truck for evaluation or sale

Owners can compare options more effectively when accurate information is available for each vehicle.

• Identity: Year, make, model, VIN, GVWR, and configuration.
• Mileage and hours: Odometer, engine hours, and relevant auxiliary or power-take-off hours where available.
• Mechanical condition: Known engine, transmission, brake, emissions-system, electrical, or other problems.
• Operating status: Whether the truck starts, runs, drives, rolls, and can be transported.
• Body and upfit: Box or dump body, tank, crane, hydraulic system, liftgate, refrigeration equipment, and other installed components.
• Maintenance records: Service history, major repairs, inspection results, and available diagnostics.
• Ownership: Title or other applicable documentation, lien details, and authority to sell.
• Location: Vehicle ZIP code, storage arrangement, and access for inspection or transport.
• Photographs: Exterior, interior, odometer, equipment, and visible damage where practical.
• Fleet identifiers: Unit number, location, and consistent condition notes for multiple units.

Disclose important faults rather than describing older equipment as roadworthy without adequate evidence. A non-running truck can still have resale potential, but completeness, condition, ownership, and transport needs matter.

Title transfers, lien resolution, environmental handling, and disposal procedures vary by jurisdiction and transaction. Verify the applicable requirements before a sale or dismantling arrangement.

What happens to commercial trucks after they leave a fleet?

The next destination depends on vehicle condition, commercial value, regulatory eligibility, and the owner’s choice. There is no single retirement pathway.

Secondary service: A complete truck may be sold for different routes, lower-intensity work, or another business use, subject to safe and lawful operation.

Storage: An owner may keep a truck while deciding whether to repair, sell, or dismantle it. Storage does not, by itself, establish the end of physical life.

Export: A vehicle may be exported where lawful. Leaving U.S. registration records does not necessarily end worldwide operation.

Parts recovery: Engines, transmissions, axles, bodies, and other usable components may be recovered when complete-vehicle resale is impractical.

Material recycling and disposal: Permanently dismantled trucks may yield recoverable materials. Oils, fuel, coolant, batteries, refrigerants, and other materials can require appropriate handling under applicable environmental rules.

The downstream fate of a truck cannot be inferred simply because its owner decides to sell it or stop using it. EasyTruckBuyer is a truck-buying business; this analysis does not represent the company as operating its own scrapyards, dismantling centers, or environmental recycling programs.

Frequently asked questions

Conclusion: What the evidence establishes

Federal data show a substantial U.S. truck population and meaningful differences in how truck categories are used. FHWA’s 2024 edition reports approximately 16.1 million single-unit and combination-truck registrations, with combined road mileage remaining nearly level between 2023 and 2024.

Census/BTS survey information provides additional evidence about truck configurations, age, and utilization. EPA models use survival-related assumptions that support emissions estimation but do not establish a newly observed physical-scrappage rate.

These sources cannot be transformed into a defensible annual Classes 3-8 scrappage count without additional comparable evidence on entries, exports, administrative changes, and verified destruction.

For researchers, the priority is better longitudinal and cross-source reconciliation. For fleet managers, condition, operating needs, maintenance, and economic alternatives are more informative than an unsupported industry-wide retirement age. For owners, leaving current service may still be followed by repair, resale, reassignment, or other lawful disposition.

Methodology, limitations, and research transparency

Publication classification

This is an evidence review and federal-data analysis with original descriptive calculations. It is not a proprietary commercial truck retirement study, an independently conducted survey, a nationally representative physical-scrappage measurement, or a peer-reviewed original research paper.

Research approach

The analysis reviewed publicly available government statistics, federal technical documentation, official regulatory information, and a relevant peer-reviewed comparison of survey and emissions-model populations.

The principal numerical analysis uses FHWA Highway Statistics 2024, Table VM-1. Supporting evidence includes the 2021 Census/BTS VIUS, historical ORNL survival models, EPA MOVES6 documentation, and official sales, trade, and regulatory resources.

Research checked October 20, 2026. This is not a claim that the article was published on that day. The editorial attribution for this analysis is EasyTruckBuyer as the publishing organization, with no invented named analyst or credential.

Calculation record

Method: Calculations use FHWA’s published totals and category averages. Percentages and ratios are rounded as in the audited master. These calculations do not reconstruct individual vehicle histories or estimate actual physical scrappage.

Major data limitations

• Different populations: FHWA categories, Census survey populations, EPA source types, and retail-sales definitions are not directly interchangeable.
• Different reference years: FHWA figures concern 2023-2024, VIUS concerns 2021, and ORNL survival inputs concern much older model years.
• Survey coverage: Standard 2021 VIUS excludes government-owned and certain other vehicles. New Hampshire is omitted from the standard sample and modeled in a separate experimental product.
• Model dependence: EPA default age distributions incorporate historical survival assumptions rather than direct current scrappage observations.
• Registration comparability: State reporting and estimation can change; FHWA documents a New York reporting transition in 2024.
• Incomplete destruction evidence: The sources do not isolate every physically scrapped truck from exported, inactive, reclassified, or otherwise absent vehicles.
• Unquantified uncertainty: No new VIUS weighting, cohort modeling, or nationally representative destruction analysis was performed. No unsupported confidence intervals are offered.

What this analysis does not establish

• The annual number of Classes 3-8 trucks physically scrapped nationwide.
• A universal current commercial-truck scrappage percentage.
• A modern observed average physical lifespan for every Class 8 or vocational-truck category.
• A complete national used-commercial-truck export count.
• The number of older trucks physically scrapped after the 2024 registration changes.
• A forecast retirement wave based only on the published registration figures.
• A proprietary EasyTruckBuyer truck-retirement dataset.

Unknown values are left unknown rather than filled with guessed assumptions. The distinction between published agency estimates, descriptive arithmetic, historical models, and interpretations is maintained throughout.

Primary references

1. Federal Highway Administration. Highway Statistics 2024, Table VM-1: Annual Vehicle Distance Traveled in Miles and Related Data. Updated February 2026. Official source.
2. Federal Highway Administration. Highway Statistics 2024, Table MV-1: State Motor-Vehicle Registrations. January 2026. Official source.
3. U.S. Department of Energy, Alternative Fuels Data Center. Vehicle Weight Classes and Categories. Agency data directory.
4. U.S. Census Bureau. About the Vehicle Inventory and Use Survey. Survey scope and exclusions. Official source.
5. U.S. Census Bureau. 2021 Vehicle Inventory and Use Survey Tables. September 2023. Official source.
6. U.S. Census Bureau. Vehicle Inventory and Use Survey National Estimates With Modeled Estimates for New Hampshire. September 2023. Official source.
7. Bureau of Transportation Statistics. VIUS Summary Statistics Report. January 22, 2026. Official report.
8. Oak Ridge National Laboratory. Transportation Energy Data Book, Edition 40. 2022. Official publication.
9. U.S. Environmental Protection Agency. Population and Activity of Onroad Vehicles in MOVES6. EPA-420-R-26-010, August 2026. Technical report.
10. U.S. Environmental Protection Agency. MOVES6 Update Log. Initial model release September 2026. Official release information.
11. International Journal of Sustainable Transportation. Improving Commercial Truck Fleet Composition in Emission Modeling Using 2021 US VIUS Data. December 2025. Research DOI.
12. U.S. Bureau of Economic Analysis via FRED. Motor Vehicle Retail Sales: Heavy Weight Trucks. Series HTRUCKSNSA. Official data series.
13. U.S. International Trade Commission. DataWeb, U.S. merchandise-trade statistics. Official database.
14. U.S. Environmental Protection Agency. Final Rule: Rescission of the Greenhouse Gas Endangerment Finding and Motor Vehicle Greenhouse Gas Emission Standards. February 2026. Official rule summary.
15. U.S. Environmental Protection Agency. Regulations for Smog, Soot, and Other Air Pollution From Commercial Trucks and Buses. Official program page.
16. California Air Resources Board. Truck and Bus Regulation. Official state program.
17. U.S. Environmental Protection Agency. Diesel Emissions Reduction Act State Grants. 2025-2026 program documents and scrappage requirements. Official program.