Why It Matters
A new bill presents a conflict between federal environmental regulations and operational safety in extreme winter climates. Sen. Dan Sullivan (R-AK), the bill’s primary champion, argues current EPA mandates are "failing in sub-zero temperatures, creating dangerous situations where engines lose power or shut down entirely."
The bill would authorize the EPA Administrator to allow vehicle manufacturers to temporarily suspend engine "derate" or shutdown functions during prolonged cold weather. When Diesel Exhaust Fluid (DEF) freezes at approximately 12°F, EPA regulations mandate that vehicles reduce power or shut down entirely. In remote, sub-zero conditions, such shutdowns can be life-threatening.
Environmental advocates and Democratic senators argue that weakening these regulations could undermine critical progress on air quality and climate goals. Ranking Member Sheldon Whitehouse (D-RI) is expected to defend EPA’s regulatory authority, viewing such measures as part of a broader rollback of environmental protections.
Broader Context
The Senate hearing on S. 3135 arrives amid a dramatic shift in EPA enforcement. In February 2026, the Trump administration repealed the Obama-era endangerment finding and eliminated federal tailpipe emissions standards, emboldening industry appeals for exemptions.
EPA Administrator Lee Zeldin acknowledged DEF system failures as "a massive issue", demanding manufacturer data in February 2026. Current EPA guidance already permits warning-light-only responses for 650 miles after DEF faults, signaling administrative flexibility.
Sens. Sullivan and Lummis (R-WY) introduced the bill to allow manufacturers to suspend derates during extreme cold. A House companion bill from Rep. Nick Begich (R-AK) followed in November 2025.
The Agenda
Industry witnesses are expected to include representatives from the National Truck Equipment Association, which spent $40,000 each in second and third quarters in 2025 lobbying on related EPA emissions resolutions, and Phillips 66, which invested $1.74 million in first quarter 2025 lobbying on EPA vehicle emission rules.
Environmental witnesses are expected to align with Ranking Member Whitehouse, who has condemned the EPA’s "wholesale assault on environmental protections."
Competitive Landscape
Industry is mobilizing heavily. The National Truck Equipment Association spent $40,000 in both second and third quarters lobbying on EPA emissions resolutions. Phillips 66 deployed $1.74 million in Q1 2025 opposing EPA vehicle regulations, plus an additional $60,000 through Crossroads Strategies in second quarter 2025. Both organizations have also opposed S. 996, the Preserving Choice in Vehicle Purchases Act. The coordinated effort signals the trucking and energy sectors view S. 3135 as part of a broader agenda targeting EPA authority over vehicle emissions.
The Bottom Line
The core tension is whether a targeted exemption for extreme-weather operations represents reasonable regulatory flexibility or opens the door to broader erosion of emissions standards. The hearing will reveal congressional appetite for accommodating industry concerns within an accelerating deregulatory environment.
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