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At Munro & Associates, we specialize in benchmarking and reverse engineering. But sometimes, it’s just as valuable to take a moment and appreciate the engineering behind a modern hybrid vehicle. The 2025 Hyundai Santa Fe Hybrid offers us that perfect opportunity. Not only is it a solid example of what a parallel hybrid can be, but it also opens the door for us to explore how hybrid systems work and why certain choices are made in their design.
Balancing Power and Practicality
The Santa Fe Hybrid is a midsize SUV that delivers on both practicality and efficiency. Powered by a 1.6-liter turbocharged engine that produces 178 horsepower, it’s paired with a six-speed automatic transmission. This isn’t a continuously variable transmission (CVT) or an electrified version of something new. This is a traditional six-speed gearbox mated with clever hybrid tech.
Between the engine and the transmission lies a slim, 40-millimeter section that houses a 60-kilowatt electric motor and a clutch. This configuration is what makes the Santa Fe a “parallel hybrid.” In this setup, either the internal combustion engine (ICE), the electric motor, or both can power the vehicle—working in parallel, hence the name. A clutch allows the system to decouple the ICE when needed. This lets the vehicle operate purely on electric power in certain scenarios.
One of the biggest benefits of this approach is cost. By retaining much of the traditional internal combustion drivetrain—engine, transmission, driveshafts—Hyundai can implement a hybrid solution without a complete redesign. All it takes is inserting the motor and battery into an existing architecture. That means lower manufacturing costs and fewer changes to the vehicle’s structure.
However, there are some limitations. While a parallel hybrid offers decent fuel efficiency gains, it’s not as sophisticated in its energy management or performance optimization as other types of hybrid systems. That brings us to the other major hybrid approach—power-split hybrids. This has been popularized by the Toyota Prius and now adopted in vehicles like the RAV4, Honda CR-V, and Ford Escape Hybrid.
How the Santa Fe Hybrid Maximizes Every Mile
Before diving into the differences, it’s worth celebrating what Hyundai has accomplished with this model. The Santa Fe Hybrid achieves a commendable 34 miles per gallon (combined), performing slightly better in city driving than on the highway. That’s the opposite of what you typically see in non-hybrid vehicles. This speaks to the benefits of regenerative braking and electric motor assist during stop-and-go driving.
The rear wheels are mechanically driven via a traditional differential and driveshaft. This is complete with a disconnect system that reduces drag when not in use—another efficiency boost. Regen braking allows the electric motor to act as a generator, capturing kinetic energy when slowing down and storing it in the battery. That stored energy then provides electric assist during acceleration, reducing fuel consumption. You also gain secondary benefits like powering vehicle accessories without relying on an alternator, which would otherwise create parasitic drag on the engine.
Complex Architecture, Exceptional Efficiency
Now, let’s turn to the power-split hybrid system—a completely different beast in terms of architecture and capability. First introduced in the Prius, the power-split system is now widely adopted. It uses a planetary gearset to manage power flow between the engine, electric motors, and wheels. This setup typically involves two electric motors—Motor A and Motor B. The engine sends power into the planetary gearset, where Motor A can vary the speed of the sun gear, effectively creating a continuously variable transmission (CVT) without belts or pulleys.
This design is more complex than the parallel hybrid but offers significant fuel economy benefits. By allowing the engine to always operate in its most efficient speed and load range, power-split hybrids optimize fuel consumption under a wide range of driving conditions. The electric motors play multiple roles—driving the wheels, managing regenerative braking, and even determining gear ratios dynamically.
What’s fascinating is that despite this complexity, the power-split system ends up with similar or even better efficiency compared to traditional multi-speed transmissions. That’s because the majority of power still travels through the mechanical gearset—around 90-95%. Only a small portion routes through the electric path, which is slightly less efficient but more flexible.
Why Hybrid Systems Take Many Forms
There’s a tradeoff, of course. Power-split systems require two electric motors, two inverters, and a uniquely tuned engine—often using the Atkinson cycle, which emphasizes peak thermal efficiency over raw torque. While this makes for stellar fuel economy, it necessitates electric assist during acceleration to compensate for the engine’s low-end torque deficiency.
But this tradeoff is by design. The Atkinson-cycle engine is optimized to stay in its “happy zone,” the ideal speed and load range for maximum efficiency. The electric motors handle the rest, especially during low-speed or high-load conditions. This synergy is what makes the power-split hybrid so compelling for automakers who want to push fuel economy without sacrificing drivability.
That said, the Santa Fe’s parallel hybrid system is a clever and effective solution in its own right. It allows Hyundai to bring hybrid technology to market quickly and affordably, making it more accessible to families looking for better fuel economy without stepping into full electrification.
Perhaps one of the most compelling parts of this hybrid discussion is how it connects engineering history. While Toyota gets credit for popularizing the power-split design, the concept actually dates back to 1902, when engineer John Henry of Boulder, Colorado invented and documented a similar setup. Thanks to his wife (who patented the design posthumously), this concept is now part of the public domain, forming the backbone of many modern hybrid systems.
Innovation Through Simplicity
In conclusion, the 2025 Hyundai Santa Fe Hybrid is a shining example of what can be accomplished with a thoughtful, practical approach to hybridization. While it doesn’t use the more complex power-split design, it achieves impressive real-world efficiency and performance. It also demonstrates that there’s no single “right” way to build a hybrid. Instead, it’s about understanding the tradeoffs and applying the right technologies in the right places. And, ultimately, delivering value to the customer.
As hybrid systems continue to evolve, and battery costs and technologies improve, even more creative configurations are likely to emerge. But for now, vehicles like the Santa Fe remind us that innovation doesn’t always mean reinventing the wheel. Sometimes, it just means refining it.
Stay tuned for more deep dives like this from the team at Munro Live.