Nissan E Power

[ZZman]

https://www.cnbc.com/2026/03/21/nissan-series-hybrid-rogue-suv.html

I always thought this would be the way to go. Make the engine specifically for electricity generation to keep battery charged.

 

[Boomer]

What about the efficiency? I guess you could run the engine at peak constant RPM but there have to be losses in generation of electricity and charging. I am curious as to what advantage this offers over a regular high efficiency ICE set up?

 

[ka9mnx]

It's worked for Diesel locomotives for over 70 years.

 

[fdcg27]

This would seem to be inherently less efficient that the parallel hybrid systems that Toyota and Honda use.
It will also be simpler and cheaper, so if it can deliver the kind of fuel economy improvements Nissan is suggesting then it will find a place in the market.

 

[DCDG]

Chevy Volt returns as a Nissan, interesting. Mazda is supposedly working on this style of a hybrid with a generator that's uses a single rotary engine. And according to Mazda super efficient and great power output to weight/size ratio.

 

[Boomer]

I understand it works like a diesel locomotive. I am questioning the efficiency. My Passat has a Budack (sp?) 4 cylinder engine and on trips from PA to FL, I get about 42-44 mpg highway on a reproducible basis. That is a large sedan as well.

BTW, locomotives use that setup as it would basically be impossible to start a train with a clutch or auto transmission .

 

[ZZman]

What about the efficiency? I guess you could run the engine at peak constant RPM but there have to be losses in generation of electricity and charging. I am curious as to what advantage this offers over a regular high efficiency ICE set up?

My thought on efficiency would be to use a diesel engine and use its high torque to spin a stronger generator

 

[jghall00]

What about the efficiency? I guess you could run the engine at peak constant RPM but there have to be losses in generation of electricity and charging. I am curious as to what advantage this offers over a regular high efficiency ICE set up?

My understanding is that it's more akin to driving an electric vehicle because you get the torque and regen that electric motors provide. The gas engine always operates in the most efficient mode. The powertrain has been available overseas for several years so there are mpg tests. Bjorn Nyland tested one.

 

[Torrid]

It's worked for Diesel locomotives for over 70 years.

For reliability, not efficiency.

 

[jghall00]

My thought on efficiency would be to use a diesel engine and use its high torque to spin a stronger generator

Cost, maintenance, and emissions make this a non starter. There's a reason diesels are primarily used in commercial vehicle applications.

 

[ka9mnx]

Mother Earth News published a how to article in the 70's. An 18hp Wisconsin engine turned a generator at a constant speed which powered a bank of batteries which ran a DC electric motor which powered the car. Crude but it worked.

 

[ka9mnx]

For reliability, not efficiency.

True. Reliability, ease of maintenance and range. Steam locos needed a lot of maintenance after every trip. They needed coal and water every 100 miles.

 

[alarmguy]

I like the idea and according to @jghall00 have been proven overseas.

 

[jghall00]

I like the idea and according to @jghall00 have been proven overseas.

Here's the development history from Nissan.

And a post from someone familiar with the powertrain and mpg.

 

[DCDG]

Similar design and concept https://www.motoringresearch.com/car-reviews/mazda-mx-30-r-ev-2024-review/

 

[jghall00]

Similar design and concept https://www.motoringresearch.com/car-reviews/mazda-mx-30-r-ev-2024-review/

Mazda sold the MX30 without the rotary in the US very briefly. As you can imagine, it had limited range with its small battery and was a complete non-starter in the market.

I'm unsure whether Mazda ever resolved the numerous issues with the rotary, primarily seals and emissions due to oil consumption. The characteristics of the engine make it attractive for use an extender (compact, low vibration) if they can fix some of the shortcomings. I think some of the issues go away when it has a narrow operating range.

There's a startup, Liquid Piston, that claims to have addressed the biggest issues. But I've seen many ICE startups come and go before their designs are commercialized so not holding my breath in a world with 10C charging.

 

[DCDG]

Mazda sold the MX30 without the rotary in the US very briefly. As you can imagine, it had limited range with its small battery and was a complete non-starter in the market.

I'm unsure whether Mazda ever resolved the numerous issues with the rotary, primarily seals and emissions due to oil consumption. The characteristics of the engine make it attractive for use an extender (compact, low vibration) if they can fix some of the shortcomings. I think some of the issues go away when it has a narrow operating range.

There's a startup, Liquid Piston, that claims to have addressed the biggest issues. But I've seen many ICE startups come and go before their designs are commercialized so not holding my breath in a world with 10C charging.

I understand in this approach Mazda was using a rotary designed generator to keep the electrical drive battery charged/topped off. Similar to the Chevy Volt and I assume what Nissan intends to do on their E-power design. So not really new technology I always did like the Chevy Volt just wasn't the right time.

 

[robbobster]

Conversion always introduces loss. Always.

It is more efficient to spin an ICE to directly turn the driven wheels…versus spinning an ICE to turn a generator to send electricity to turn an electric motor to turn the driven wheels.

Locomotives are a specific use case. When it comes to getting a train moving, generating massive torque at zero rpm was a huge improvement over steam engines.

But a series hybrid can make a lot of sense for other reasons. Ram has one in development also, makes sense for a working truck.

 

[y_p_w]

True. Reliability, ease of maintenance and range. Steam locos needed a lot of maintenance after every trip. They needed coal and water every 100 miles.

The city Coalinga, California was allegedly named for what was known as Coaling Station A.

 

[jghall00]

Conversion always introduces loss. Always.

It is more efficient to spin an ICE to directly turn the driven wheels…versus spinning an ICE to turn a generator to send electricity to turn an electric motor to turn the driven wheels.

That may be true, but it's possible that other optimizations make the conversion losses worthwhile because most of the loss is on the ICE side, so gains there have a disproportionate impact on the efficiency of the overall system. ICE has a narrow range for efficiency. By using it as a generator, it can stay closer to this optimal range. In addition, Atkinson cycle can be employed to boost efficiency since peak power isn't frequently needed. You also acquire the ability to use regen braking to recapture energy that would be lost as heat. I'm not sure why a series hybrid would be better than a parallel hybrid like Toyota or Honda's implementation, but I'm fine with manufacturers experimenting. According to Gemini a series hybrid is less efficient on the highway due to the conversion losses, which makes sense.