What is Nissan's e-POWER? (2nd & 3rd Gen Compared)

Added: 2026-05-30

[00:00:03]This channel provides easy-to-understand explanations of car mechanisms.

[00:00:10]This video provides an overview of four key hybrid systems takes a detailed look at series hybrids, and compares Nissan’s 2nd and 3rd generation e-POWER with their main competitors.

[00:00:24]Hybrid systems can be classified into four types: power-split, parallel, series, and series-parallel.

[00:00:33]To avoid overcomplicating the topic, this video will focus on self-charging hybrids and exclude plug-in hybrids.

[00:00:41]While most automakers opt for the other three configurations, only Nissan and Japanese compact car specialist Daihatsu have adopted the series hybrid system.

[00:00:53]Daihatsu uses this system in a compact SUV equipped with a 1.2-liter engine and as I’ll explain later, this actually makes perfect sense.

[00:01:03]Nissan, on the other hand, is the only manufacturer using it in larger segments, like midsize SUVs and minivans.

[00:01:12]Which means, there’s a clear reason why other carmakers have chosen to steer clear of it.

[00:01:25]A parallel hybrid incorporates an electric motor and a clutch between the ICE (Internal combustion engine) and the transmission, allowing the ICE to be disconnected from the drivetrain.

[00:01:36]The main advantages of this system are that we can leverage existing ICE platforms and that the driving feel remains close to a conventional ICE-powered vehicle.

[00:01:46]However, the improvement in fuel economy is relatively modest.

[00:01:51]This architecture is adopted by automakers such as Stellantis, Audi, Toyota, and Hyundai.

[00:01:58]Furthermore, high-performance sports cars from the likes of Porsche and Ferrari utilize this system as well.

[00:02:06]A series hybrid uses the ICE exclusively to drive a generator, while the vehicle itself is propelled solely by an electric motor.

[00:02:15]It consists of the ICE, a generator, an inverter, a high-voltage battery, and a traction motor.

[00:02:22]Because the ICE is dedicated entirely to power generation, it is not involved in propelling the vehicle whatsoever.

[00:02:31]A series-parallel hybrid builds upon a series hybrid by adding a lock-up clutch, allowing the ICE to directly propel the vehicle depending on driving conditions.

[00:02:41]At low to medium speeds, where electric motors are highly efficient, the clutch is disengaged and the system operates as a series hybrid.

[00:02:50]During highway cruising, the ICE becomes more efficient; the clutch engages, and the ICE takes over to propel the vehicle directly.

[00:03:00]Some models also incorporate a 2 to 4-speed transmission in addition to the clutch to further optimize efficiency.

[00:03:07]This architecture is adopted by automakers such as Honda, Mitsubishi, and several Chinese manufacturers.

[00:03:15]Combined with its excellent fuel economy and an acceleration feel close to that of a pure EV, it might be considered one of the most well-balanced systems.

[00:03:26]The power-split hybrid architecture is predominantly used by Toyota, Ford, and Subaru.

[00:03:33]This system consists of an ICE, a planetary gear-type power split device, MG1 (Motor Generator), which mainly operates as a generator and starter motor for the ICE, and MG2, which is primarily used to propel the vehicle.

[00:03:50]From a standstill to low-speed driving, the vehicle operates in EV mode, with MG2 solely propelling the vehicle.

[00:03:58]Once the vehicle speed exceeds a certain threshold, the ICE is started to provide propulsion.

[00:04:05]At this stage, the power-split device functions as an CVT (Continuously Variable Transmission), allowing the ICE to operate within its most efficient speed range.

[00:04:17]Compared to other systems, it is widely recognized that this architecture offers some of the highest fuel efficiency.

[00:04:25]This channel prepared a video that explains power-split and series-parallel hybrid in detail.

[00:04:30]If you’re interested, please check it out. You'll find the link in the description.

[00:04:41]Let’s consider the advantages and disadvantages of series hybrids compared with series-parallel hybrids.

[00:04:48]Series-parallel hybrids need an oil pump that generates high hydraulic pressure to operate the lock-up clutch, which causes energy loss.

[00:04:57]Series hybrids are also equipped with an oil pump to lubricate and cool the motors and gears inside the unit, but it does not need to generate high hydraulic pressure.

[00:05:06]As a result, in the low to mid-speed ranges, losses are minimized, resulting in superior fuel economy.

[00:05:14]This helps explain why Daihatsu adopted a series hybrid system for its compact SUV, where high-speed fuel efficiency is not a major priority.

[00:05:24]In fact, the first vehicle in which Nissan adopted this system was a compact hatchback with a 1.2-liter engine.

[00:05:33]The drawback is high-speed fuel efficiency.

[00:05:36]There are two reasons for this.

[00:05:39]The first is the characteristics of electric motors.

[00:05:44]These graphs show the typical torque curves of a gasoline engine and an electric motor.

[00:05:49]You can see that gasoline engines are most efficient in the mid-speed range, while electric motors are highly efficient at low speeds.

[00:05:57]For this reason, series-parallel hybrids engage a lock-up clutch and switch to engine drive mode during highway cruising.

[00:06:06]However, series hybrids must continue using the electric motor even when its efficiency is low.

[00:06:14]The second reason is the repetition of energy conversions.

[00:06:19]In a series hybrid, the engine’s mechanical energy is first converted into electrical energy by a generator.

[00:06:26]Since the conversion efficiency is not 100%, some energy is lost during this process.

[00:06:33]The generated electricity is alternating current, with a frequency based on the engine speed.

[00:06:39]This is converted into direct current by the traction inverter, where energy is also lost.

[00:06:45]To obtain the traction motor speed requested by the driver, the inverter converts the direct current back into alternating current, causing another energy loss.

[00:06:55]Finally, since the efficiency of the traction motor is also not 100%, energy is lost during motor operation as well.

[00:07:03]Consider a situation where the vehicle is traveling at a constant speed on the highway.

[00:07:08]Let us assume both engines have a thermal efficiency of 40%.

[00:07:14]In this case, since the series-parallel hybrid is operating in engine drive mode, if we ignore gear losses, it can transmit that full 40% of the gasoline’s energy straight to the wheels.

[00:07:26]In contrast, a series hybrid suffers losses at four distinct points: the generator, the inverter’s AC-to-DC conversion, the DC-to-AC conversion, and the traction motor.

[00:07:38]Assuming each point operates at 95% efficiency, only 81% of the energy produced by the engine actually reaches the wheels.

[00:07:47]In other words, only about 33% of the energy contained in the gasoline is being used effectively.

[00:07:54]Nissan has introduced a series hybrid version of its midsize SUV equipped with a 1.5-liter turbo engine known as the X-Trail or Rogue depending on the market in several regions.

[00:08:06]However, it is widely rumored that the company abandoned plans to export this model to North America, its largest market, due to its poor highway fuel efficiency.

[00:08:22]Nissan brands its series hybrid system as “e-POWER.”

[00:08:27]The e-POWER system used in the Nissan X-Trail, or Rogue, is the second-generation version.

[00:08:33]The engine is a 1.5-liter three-cylinder VC-Turbo.

[00:08:38]“VC” stands for Variable Compression.

[00:08:41]It is a groundbreaking engine that can vary its compression ratio between 8.0:1 and 14.0:1, using a complex multi-link mechanism integrated into the crankshaft.

[00:08:53]However, this expensive and complex system while highly effective in a conventional gasoline vehicle is arguably excessive for an engine dedicated solely to driving a generator.

[00:09:05]Let’s compare its fuel economy with that of thae power-split Toyota RAV4 and the series-parallel Honda CR-V.

[00:09:13]All data is sourced from Germany's ADAC Autodatenbank.

[00:09:18]First, let's look at the maximum power and torque of the ICE and traction motor.

[00:09:24]Compared to Toyota, which propels the vehicle using a combination of ICE and traction motor power, Honda and Nissan rely solely on their motors for propulsion, necessitating much more powerful electric motors.

[00:09:37]WLTP fuel economy.

[00:09:41]Since the unit is liters per 100 kilometers, a lower bar, indicates better fuel economy.

[00:09:48]Toyota overwhelmingly outperforms the others.

[00:09:51]However, the fact that Honda’s high-speed fuel economy appears worse than Nissan’s seems to contradict the thesis of this video.

[00:09:59]But fear not. This is where things get truly interesting.

[00:10:04]To find the answer, we look to the real-world highway fuel economy tests conducted by the YouTube channel, "1001 Cars."

[00:10:13]As these are real-world public road tests, environmental conditions vary slightly, and the drivetrain configurations whether FWD or AWD are not specified.

[00:10:25]Furthermore, because the current-generation RAV4 has not yet been featured on their channel, we are utilizing data from the previous generation.

[00:10:34]While these figures may lack laboratory precision, they are more than adequate to capture the overall trend.

[00:10:40]Take a look at the results.

[00:10:43]As you can see, the core argument of this video is perfectly vindicated by these real-world numbers.

[00:10:50]Remember, standard WLTP testing consists entirely of transient driving cycles with continuous acceleration and deceleration, completely excluding steady-state cruising.

[00:11:02]Yet, when driving long distances, most drivers spend extended periods maintaining a constant speed on the highway.

[00:11:15]However, Nissan wasn't just turning a blind eye to this inherent drawback.

[00:11:21]In 2024, they introduced the Qashqai, equipped with their third-generation e-POWER to the European market.

[00:11:29]While there were likely countless improvements, we’re going to single out three major ones.

[00:11:35]The engine was changed from the variable-compression turbocharged KR15DDT to the fixed-compression turbocharged ZR15DDTe.

[00:11:46]Fitting a larger turbocharger reduces low-rpm response, but improves efficiency within a specific engine speed range.

[00:11:55]This is an approach that would be impractical in a conventional ICE-powered vehicle, but it is possible with an ICE dedicated solely to driving a generator.

[00:12:06]In extreme terms, even if the ICE revs up three seconds after the driver presses the accelerator pedal, it would not be a problem, because the traction motor would accelerate the vehicle during that period.

[00:12:19]Based on this architectural approach, Nissan sacrificed some of the characteristics normally expected of a conventional ICE in order to achieve higher efficiency.

[00:12:30]The KR15DDT has a peak thermal efficiency of approximately 38.7%, while the ZR15DDTe achieves around 42%.

[00:12:43]Inside the inverter, the power transistors repeatedly switch the current on and off in order to convert direct current into alternating current.

[00:12:52]In the third-generation e-POWER, conventional silicon power transistors made way for highly efficient silicon carbide components.

[00:13:00]While silicon carbide transistors are becoming standard in battery EVs, where squeezing out every watt of efficiency is a top priority, their application in a hybrid vehicle is highly unusual.

[00:13:12]And the reason comes down to cost.

[00:13:16]In engineering, not just in the automotive world, cost and performance are always weighed against each other.

[00:13:21]Yet here, Nissan chose performance.

[00:13:25]Furthermore, Nissan improved the efficiency of the traction motor at high rotational speeds.

[00:13:32]They significantly reduced internal magnetic resistance, known as "iron loss," which typically plagues motors at higher rotational speeds.

[00:13:41]Here is a conceptual graph to visualize this transition.

[00:13:47]Now, let’s finally look at the data for the Qashqai, featuring the third-generation e-POWER incorporated with all these improvements.

[00:13:55]First, we will compare the maximum power and torque of the ICE and the traction motor.

[00:14:02]Even without the variable compression mechanism, it delivers nearly the same power and torque as the previous generation.

[00:14:09]WLTP fuel economy.

[00:14:13]Unbelievable!

[00:14:15]Not only has it pulled far ahead of Nissan’s previous system and Honda's, but it has even surpassed Toyota’s.

[00:14:23]Now, here are the real-world fuel economy figures you've been waiting for.

[00:14:28]Astonishing!

[00:14:30]It is almost on par with Toyota’s.

[00:14:33]Of course, this result comes with a few caveats.

[00:14:38]The Toyota used for comparison is an older model, and the Qashqai is FWD, while the drivetrain layouts for the other three vehicles remain unspecified.

[00:14:48]Furthermore, the Qashqai has a slightly smaller body than the other three, giving it a clear weight advantage Therefore, we must keep in mind that this is not an entirely apples-to-apples comparison.

[00:15:01]However, one thing we can say for certain is that the evolution of the third-generation e-POWER is truly remarkable.

[00:15:09]This summer, Nissan will introduce a new minivan equipped with the third-generation e-POWER to the Japanese market.

[00:15:17]And Toyota’s formidable minivans, are already waiting for it.

[00:15:21]Looking ahead, this technology will undoubtedly filter down to the X-Trail, known as the Rogue in North America.

[00:15:29]And that is when we will see the true potential of Nissan's latest hybrid evolution.

[00:15:36]Thank you for watching.

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[00:15:43]We'll see you in the next video!