For U.S. fleet owners and operators, the math of the “daily grind” has never been more scrutinized. Between fluctuating diesel prices, the looming EPA 2027 regulations, and a persistent shortage of seasoned drivers, the margin for error is razor-thin. In this environment, “good enough” fuel efficiency is a fast track to being uncompetitive.

Every manufacturer promises better MPG, but it is rare to see a “clean-sheet” redesign that fundamentally changes the physics of the powertrain. That is why the industry has been laser-focused on the International® S13 Integrated Powertrain.

To provide transparency into how this system performs under pressure, International recently published a deep dive into their latest benchmarks: Testing for Improved Truck Fuel Efficiency.

If you are currently evaluating your 2026 or 2027 procurement strategy, here is why this specific testing data matters for your bottom line.

The Power of Integration: More Than the Sum of Its Parts

The S13 isn’t just a new engine; it’s an integrated powertrain consisting of the engine, the T14 automated manual transmission, and the Dual-Stage Aftertreatment system. Traditional “pick-and-mix” component strategies often lose efficiency at the connection points. By designing these three components to speak the same language, International has achieved a level of synergy that was previously impossible.

The result? Testing confirms up to a 15% gain in fuel efficiency over the previous generation. For a fleet running 100,000 miles per year per truck, that 15% isn’t just a statistic—it’s a massive injection of liquidity back into your business.

Why “No Cooled EGR” is a Game Changer

One of the most compelling aspects of the S13 testing is the performance of its simplified engine architecture. Most heavy-duty engines rely on Cooled Exhaust Gas Recirculation (EGR) to reduce emissions, which sends soot-heavy air back into the combustion chamber. This creates heat, requires massive cooling packages, and leads to frequent DPF regenerations.

The S13 does away with the cooled EGR entirely. By utilizing a dual-stage aftertreatment system, the engine runs cleaner and cooler. This means the energy previously wasted on managing heat and “cooking” the DPF is now used for one thing: moving the wheels forward. For operators, this translates to fewer “forced regens” and significantly higher uptime.

Driver-Centric Efficiency

Fuel efficiency isn’t just about the hardware; it’s about how the driver interacts with the machine. The S13 testing highlights the role of the T14 transmission, which uses electronic clutch actuation for faster, smoother shifts.

The testing data shows that by minimizing the interruption of power during shifts, the truck maintains its momentum more effectively, especially on grades. For the driver, this means a quieter cab and a less fatiguing day behind the wheel. For the owner, it means that even a novice driver can achieve MPG numbers that used to be reserved for 20-year veterans.

Real-World Testing, Real-World Results

Lab data is one thing, but the “Stories” series from International focuses on how these trucks handle the variables of the open road. From aerodynamic optimization to the way the powertrain manages “Eco Coast” logic, the latest report breaks down the technical hurdles the engineering teams overcame to hit their 2026 targets.

As we move toward a more regulated and cost-sensitive future, data is your most valuable asset. Don’t base your next multi-million dollar fleet investment on a brochure.

Read the full story and see the testing results for yourself on the International website.