Truck and Engine Manufacturers Association (EMA) President and CEO Jacqueline Gelb recently testified before the House Committee on Energy and Commerce Subcommittee on Environment in a hearing entitled “Rules of the Road: Examining Legislation to Modernize the Clean Air Act’s Mobile Source Requirements.”
In her written remarks, Gelb highlighted the critical role of diesel exhaust fluid (DEF) and selective catalytic reduction (SCR) technology in achieving near-zero emissions from modern diesel engines while delivering fuel savings for customers. Since the introduction of the Environmental Protection Agency’s (EPA) 2010 heavy-duty on-highway standards and subsequent nonroad standards, advanced diesel engines equipped with SCR systems have contributed to a nearly 79 percent reduction in NOX emissions.
“We have a decades-long history of working constructively with Congress and the Environmental Protection Agency, state regulators, fleets, equipment owners, and dealers to develop technologies that achieve significant emission reductions while preserving the performance, durability, and affordability that our customers require,” Gelb stated.
“Without a sufficient quantity of adequate quality DEF onboard the vehicle or equipment, the engine and aftertreatment systems will not function properly,” Gelb stated. “EPA determined that the operator must be induced to replenish the onboard DEF supply. However, real-world experience has shown that some inducement requirements can create operational burdens, restricting our customers’ ability to deliver their load or finish their task.”
Over the past year, EMA officials have worked with EPA to develop practical improvements to these requirements. EPA’s new guidance provides manufacturers with greater flexibility to reduce operational disruptions while still ensuring DEF is onboard and emissions systems continue to function as intended.
EMA officials commended Rep. Julie Fedorchak (R-ND) for introducing legislation to codify EPA’s guidance to reduce DEF-related burdens and operational disruptions for equipment operators, while providing manufacturers with the regulatory certainty needed to continue advancing EPA’s emissions objectives.
Gelb noted that manufacturers are working with customers in the field to address real-world operational challenges, and Rep. Fedorchak’s legislation would provide an additional layer of certainty for the industry while continuing to support compliance with emissions standards.
Gelb also expressed support for the Diesel Emissions Reduction Act of 2025, co-sponsored by Rep. Doris Matsui (D-CA) and Rep. Nick Langworthy (R-NY). The legislation would reauthorize the DERA program, a federal clean air initiative that supports projects that reduce NOX emissions from diesel vehicles, improve air quality, and protect human health. Gelb concluded,
“As Congress evaluates potential changes to DEF-related requirements, we encourage a balanced approach that ensures DEF is onboard the vehicle or equipment and preserves the fuel savings and performance needs of our customers while addressing legitimate operational impacts and user experiences,” she stated.
