Heavy Duty Trucking Logo
MenuMENU
SearchSEARCH

Report Clears EPA 2017 Glider-Emissions Study

An audit by the Environmental Protection Agency’s independent Office of the Inspector General says the agency's testing of glider kit emissions, which found they produced significantly more emissions than new vehicles, “complied with standard practices.”

David Cullen
David Cullen[Former] Business/Washington Contributing Editor
Read David's Posts
August 2, 2019
Report Clears EPA 2017 Glider-Emissions Study

An audit by the U.S. Environmental Protection Agency’s independent Office of the Inspector General has found that the glider vehicle testing conducted by the agency “complied with standard practices.”

Photo: Deborah Lockridge

4 min to read


It took a while, but an audit by the U.S. Environmental Protection Agency’s independent Office of the Inspector General has found that the glider vehicle testing conducted by the agency, which found that glider-kit vehicle put out significantly more emissions than new trucks, “complied with standard practices.”

The OIG said on July 31 that the audit stemmed from Congressional requests made in the summer of 2018  that had “raised concerns about glider vehicle testing conducted by the EPA in 2017. In response to the congressional requests, the OIG conducted an audit to examine the selection, acquisition and testing of glider vehicles at the EPA’s National Vehicle and Fuel Emissions Laboratory, as well as the EPA’s planning for this testing.”

Ad Loading...

The testing that’s been at the heart of the controversy was part and parcel to the November 20, 2017, EPA report titled “Chassis Dynamometer Testing of Two Recent Model Year Heavy-Duty On-Highway Diesel Glider Vehicles.” The key finding of the testing was, per the EPA 2017 report, that “The NOx, CO, HC, and PM emissions from the glider vehicles were significantly higher than the newer model year tractors [tested against for comparison] over all cycles.”

Critics of the study alleged that Volvo Group had undue influence with some employees at the agency, provided glider kits for testing, and that the testing was done without the approval or knowledge of agency leadership.

“The IG report puts to rest the unfounded accusations from the glider industry that a truck OEM influenced the outcomes of the glider testing results by the EPA,” Glen Kedzie, environmental affairs counsel for the American Trucking Associations, told HDT.

Ad Loading...

“We’re pleased with the inspector general’s conclusion,” John Mies, vice president of corporate communications for Volvo Trucks North America, told HDT. “We’ve said all along that all of our communication and cooperation with the EPA on this issue was entirely appropriate and part of a broad trucking industry advocacy effort.”

Glider kits have been around for decades and were originally were designed to allow refurbishing wrecked vehicles. But they gained popularity as a way for truck owners to avoid early-generation low-emissions engines that were plagued with maintenance problems and reduced fuel efficiency.  

A proposed loophole

A proposal to allow a glider kit loophole to the greenhouse gas emissions /fuel economy regulations drew criticism from all sorts of stakeholders, including environmental groups, truck and engine makers, the American Trucking Associations, some large fleets such as FedEx and PepsiCo, two former EPA administrators, some state attorneys general, and some Democratic senators.

The back story to all the back and forth on glider kits dates all the way back to October 2016. That’s when EPA and the National Highway Traffic Safety Administration issued the final GHG/Fuel Efficiency Phase 2 rule. Among other things, this rule required engines in new “glider” vehicles to meet the emissions standards for the year the vehicle was assembled, rather than for the year in which the engine powering it was manufactured.

Then in July 2017, after glider kit-maker Fitzgerald Glider Kits petitioned the agency to do so, EPA announced it intended to revisit the glider kit provisions. In November, 2017, it issued its official rulemaking proposalwhich sought to repeal emission requirements for glider vehicles, glider engines, and glider kits. That repeal proposal has yet to become a final rule. 

Ad Loading...

Fitzgerald cited a separate study by Tennessee Tech saying the remanufactured engines used in glider kits performed as well as OEM engines certified under EPA emissions standards. That study has since been discredited, with the universiy saying some of the conclusions of its study of glider kit emissions were not accurate.

Audit results

What the just-released OIG audit report states is that “EPA’s selection and testing of the donated glider vehicles in 2017 was consistent with Clean Air Act authority, standard EPA practices, and relevant policies and procedures.”

And although the OIG found that EPA did not improperly attain glider-test comparison vehicles from Volvo Trucks North America to be used for the testing, the report does state that “EPA did not fully adhere to its delegation of authority related to the acceptance of donated property under the Clean Air Act” and should instead have made sure the process was “more transparent.”

The audit also determined that:

  • EPA employees followed normal procedures in submitting the November 2017 glider vehicle test report to a public rulemaking docket.

  • There was “no evidence that EPA staff deleted materials potentially responsive to Freedom of Information Act requests or records within the scope of our audit that were related to the EPA’s 2017 glider vehicle testing.”

  • There was also “no evidence that a former Office of Transportation and Air Quality Center Director violated ethics restrictions either while serving as a federal employee or post federal employment.”

Ad Loading...

The OIG noted that it also has an audit under way that’s related to the ongoing development of the EPA’s November 2017 proposed rulemaking to repeal glider emission requirements.

According to the OIG, it is a part of the EPA, but “Congress provides our funding separate from the agency, to ensure our independence.”

More Fuel Smarts

Illustration showing DEF tank and Detroit engine
Equipmentby Deborah LockridgeJune 18, 2026

DTNA Software Update Gives Truckers More Time Before DEF Derates Take Effect

The changes reflect EPA guidance aimed at reducing downtime caused by emissions-system faults while maintaining compliance requirements.

Read More →
Illustration of exhaust aftertreatment system on an AI-inspired blue background and a green fuel pump nozzle in the foreground.
Maintenanceby Deborah LockridgeJune 15, 2026

New Agentic Predictive Maintenance Report Demonstrates How Degraded Aftertreatment Systems Waste Fuel

Questar analyzed a large mixed-class fleet and discovered it was wasting as much as $30 in fuel per vehicle, per day, because of mechanically degraded aftertreatment systems.

Read More →
Amazon electric cargo bike on New York City street
Fleet ManagementJune 15, 2026

New York City's Microhub Project is Delivering Results

Trucking, last-mile delivery companies, and environmental advocates like what they are seeing so far with New York's microhub program.

Read More →
Ad Loading...
Red Kenworth truck pulling Paper Transport trailer
Fuel Smartsby Deborah LockridgeJune 2, 2026

Lessons Learned About Alternative Fuels: Start Small, Stay Flexible

Practical advice on adopting alternative fuels and ZEVs from HDT's 2026 Top Green Fleets, from renewable diesel and natural gas to electric trucks.

Read More →
Composite image of different angles of the Kempower charger
Fuel Smartsby News/Media ReleaseMay 29, 2026

Kempower Adds Flex EV Charger to Help Support Transition to Megawatt Charging

The Kempower Mega Satellite Flex has both a CCS and MCS connector, allowing operators to serve both types of heavy-duty vehicles.

Read More →
White Hino Le electric tractor on show floor
Equipmentby News/Media ReleaseMay 26, 2026

Hino Adds Electric Class 6/7 Truck

Hino says the Le Series is an important step in the company's efforts to reduce environmental impact and support its customers’ sustainability goals.

Read More →
Ad Loading...
Sigma Powertrain BEV transmission.
Fuel Smartsby Jack RobertsMay 26, 2026

Can Multi-Speed EV Transmissions Solve Heavy Trucking’s Biggest Electric-Vehicle Problems?

A startup called Sigma Powertrain believes purpose-built multi-speed gearboxes can boost efficiency, reduce battery size and improve gradeability for heavy-duty battery-electric trucks.

Read More →
Red Hendrickson e-axle at ACT Expo booth
Equipmentby News/Media ReleaseMay 22, 2026

Hendrickson Debuts Electraax E-Axle for Medium-Duty Trucks

Developed with Driventic, Hendrickson's new integrated e-axle is designed to improve efficiency, reduce weight, and extend range in Class 6-7 EV applications.

Read More →
Fueling trucks.
Fuel SmartsCover Storyby Deborah LockridgeMay 18, 2026

50 Ways Fleets Can Cut Fuel Costs Now — Without Buying New Trucks

Fuel savings don’t come from one big change. They come from dozens of small ones. Here’s how leading fleets are stacking gains across drivers, routing, maintenance, and more.

Read More →
Ad Loading...
Collage of HDT Top Green Fleets with logo
Fuel Smartsby Deborah LockridgeMay 18, 2026

Top Green Fleets 2026: How Fleets Are Reducing Emissions in the Real World

What works in sustainable trucking today? Heavy Duty Trucking's Top Green Fleets are finding practical ways to cut fuel use, reduce emissions, and keep freight moving.

Read More →