Engines at the Center of a Recalibrated Future for Cars and Trucks

April 14, 2026

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by Allen Schaeffer (Engine Technology Forum/Motor) Engine technology is evolving to meet shifts in emissions, fuel economy, affordability, and consumer expectations in an automotive environment now more rooted in market realities than ideological policy.

After four years of electrification-focused policy, engine technology is reasserting itself as the backbone of the U.S. light-duty vehicle market. That was the clear message from our recent webinar with experts in policy analysis: Dr. Ameya Joshi of MobilityNotes and market analysis, and Alan Baum of Baum and Associates.

This session converged on a central conclusion that engine technology is evolving to meet shifts in emissions, fuel economy, affordability, and consumer expectations in an automotive environment now more rooted in market realities than ideological policy.

Policy shifts reopen the technology playbook

Recent U.S. policy developments have fundamentally altered the framework in which engine technology competes. The proposed rescission of the EPA’s 2009 greenhouse gas endangerment finding and the effective elimination of federal CO₂ standards remove the primary regulatory mechanism that favored battery electric vehicles over traditional gas and diesel engines.

At the same time, revisions to NHTSA’s Corporate Average Fuel Economy (CAFE) program—excluding EVs from setting fleet targets and eliminating noncompliance fines—shift the focus back to what internal combustion engines can deliver on their own merits.

Under this structure, fleet compliance is once again determined almost exclusively by ICE efficiency and emissions performance. This change significantly increases the value of advanced combustion strategies, hybridization, and fuel flexibility, while diminishing the role of compliance-driven EV sales. Potential revocation of California’s Clean Air Act waiver would further solidify this dynamic by aligning state standards with federal rules and removing mandated zero-emission vehicle targets.

Globally, the direction is similar.

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New gasoline engines entering production now exceed 40% peak thermal efficiency, a level once considered unattainable for mass-market vehicles.

Advanced combustion concepts—including Miller cycle operation, cooled exhaust gas recirculation, high compression ratios, and multistage high-pressure direct injection—are delivering substantial gains in both efficiency and emissions performance. The adoption rate of many engine efficiency-boosting options remains low across the wide population of vehicle classes today. That points to clear opportunities for further reductions in emissions and gains in efficiency.

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Consumer affordability anchors engine demand

Consumer economics reinforce the outlook for traditional gas and diesel engines. Rising vehicle prices, record-high monthly payments, and longer loan terms are constraining new vehicle affordability. In this environment, technologies that deliver measurable fuel economy benefits without large upfront cost premiums are strongly favored.

Internal combustion engines—especially when paired with mild or full hybridization—meet that test. They offer immediate, understandable value to buyers: lower fuel costs, familiar refueling, proven durability, and broad service infrastructure. Advanced engines and hybrids allow automakers to meet efficiency and emissions objectives while keeping vehicles within reach of mainstream households.

If anything, the last year has demonstrated that though diminished, interest in electrification remains and its growth trajectory will be delayed. The automotive sector is undergoing a swift reanchoring in engineering reality and consumer economics. Internal combustion engines are evolving into cleaner, more efficient options as an asset and not a replacement for more integrated systems that underpin hybrid and extended-range electrification strategies.

In today’s light-duty vehicle market, engine technology is no longer the problem policy must overcome. It is the platform on which practical, scalable decarbonization is being built.

To view the webinar, click here. READ MORE

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Excerpt from Engine Technology Forum/Biobased Diesel Daily: Legislation to roll back diesel-emissions regulations advancing through Congress is not in the public interest.

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Engine manufacturers are experiencing their own bout of stormy weather, having to defend technology that has been proven for 15-plus years and the success story of cleaner air and engines that are more powerful and fuel efficient. A decade and a half ago, a new emissions-control technology was introduced to achieve tightening EPA emissions standards that required a 90 percent reduction in emissions of nitrogen oxides (NOx). That technology—known as selective catalytic reduction (SCR)—is now standard on all heavy-duty diesel trucks and about half of all farm equipment. It’s an active system that requires replenishment of diesel exhaust fluid (DEF), which is 32 percent aqueous urea, at a rate of around 2 percent to 3 percent based on fuel consumption. Beyond the clean-air benefits, it yields greater fuel economy and better performance as well.

A little over a year ago, concerns from truckers and farmers about problems with SCR and DEF systems made their way to EPA. The systems are designed such that if DEF has not been refilled, it triggers a fault within the emissions-control system, and a progressive series of measures (inducements) kick in. Progressive dashboard-warning lights ultimately end with engine-power derating or inability to start until repaired. These measures are insurance policies to protect the engine and ensure it achieves EPA-certified emissions levels. SCR systems rely on a series of sensors to ensure the presence and quality of DEF and the real-time NOx emissions downstream in the exhaust—in other words, to confirm whether the system is truly reducing emissions.

Failures of sensors and other issues can ultimately result in the untimely derating of engines or shutdowns altogether. EPA responded with two sets of guidance for manufacturers (August 2025 and March 2026) to make adjustments in their compliance strategies for both new and existing engines and equipment. This will eliminate the most aggressive inducements and give significantly more time for farmers to refill DEF or to diagnose and repair a problem. The most recent guidance relieves manufacturers from having to use DEF quality sensors, which were identified to be a leading source of the reported problems.

Just as manufacturers are adjusting their compliance strategy, Congress gets involved. Hearings were held and now multiple pieces of legislation are in play. These range from a measure to eliminate DEF requirements in extremely cold climates put forth by Sen. Dan Sullivan, R-Alaska, to a bill from Rep. Victoria Spartz, R-Indiana, which eliminates emissions standards from farm equipment altogether—now included in the House-passed farm bill. It’s a 9-1-1 moment. With much invested in clean air and greater sustainability, eliminating engine-emissions standards is not in the public interest.

Fuels interests and engine makers have had their differences over the years, but they have ridden out many difficult policy challenges together—ultra-low sulfur diesel fuel and some early biodiesel mandates come to mind. But the two industries have come closer over the past decade thanks in large part to the quality commitment of the biodiesel industry and customer demand for more sustainable fuels. More manufacturers outwardly embrace biobased diesel fuels and, as John Deere has recently announced, higher blends of those fuels (B30), which send a strong signal about that relationship.

The fate and future of engine makers and fuel producers are inextricably linked. More sustainable engines using more renewable fuels lifts us up. Policies that diminish sustainability and clean air take us downward. The path is now more uneven than ever, much like the weather—one minute it is sunny and the next it is pouring rain. The only thing we can do is dress appropriately. READ MORE