Monday 9th January 2023

Mazda confirms rotary engine return for 2023

Okay, sure - it's in a range extender. But we'll take all the Wankel we can get...

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Credit to Mazda, it doesn’t exactly follow the crowd. Its ‘multi-solution’ approach to reducing greenhouse gas emissions has so far given us everything from 3.3-litre, straight-six diesels to MX-5s using man-made fuel, with every variation of hybrid and EV in between. Now it’s doing something entirely new, a move that’s been heavily previewed for a long time in fact: it’s building a rotary-powered range-extender hybrid. 

Housed inside its current MX-30, the new model will resurrect technology not seen on a Mazda since the RX-8 went out of production in 2012. Great news for the MX-30, at least, which has been hamstrung since launch by meagre range. The introduction of an electric generator supplied by a rotary powerplant will undoubtedly improve that situation. It might be the most sensible application of rotary tech in the 2020s; because it’ll operate at a constant rpm in a range extender, the inherent smoothness of the engine design will likely come to the fore. And a steady engine speed sounds the best for fuel consumption, too…

Full details are expected on Friday, when the range extender makes its debut at the Brussels Motor Show. For the moment, Mazda has confirmed little more than the existence of a ‘unique plug-in hybrid powertrain’, and that’ll be on sale in the spring. The MX-30 may not be the most PHey of small cars out there, but the reintroduction of rotary power - even in a range extender application - is nothing if not interesting. Expect to learn more by the end of the week.

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[Andy665]

Admire Mazda for ploughing their own furrow - not sure if its the right approach but will be interesting yo see what they deliver

[Scott-R]

As the owner of an i3 with range extender, I’m always amazed that more car companies didn’t follow suit. Even my 7 year old i3 has 100 miles of electric range, and I get another 80ish when running the Rex. Even today I don’t think there’s a PHEV that can match that.

Charge it when you can, put petrol in it when you can’t. It’s not perfect but it works

[otolith]

They've been used as auxiliary power units in aircraft for ages, so not untrodden ground.

As a simple, compact, lightweight range extender with excellent NVH characteristics, it has appeal. Unlikely to be very fuel efficient, but probably doesn't matter for this application. Not going to make the car in any way more interesting to drive, though.

[Johnny G Pipe]

Yep, so this is just like an i3 then, but with ditchwater-spec design and with a REx that will use oil and wear its tips out.

Progress!

[vaud]

Scott-R said:

As the owner of an i3 with range extender, I’m always amazed that more car companies didn’t follow suit. Even my 7 year old i3 has 100 miles of electric range, and I get another 80ish when running the Rex. Even today I don’t think there’s a PHEV that can match that.

Charge it when you can, put petrol in it when you can’t. It’s not perfect but it works

Me too... it feels like the best "bridge" towards EVs rather than purely going to EVs. The range extender also runs at it's most efficient mode?

[hiccy18]

Interesting, but the i3 REX was limited by small fuel range meaning you could do better with a bigger battery and no REX. I hope Mazda create a car that can handle long journeys in an effective manner, but I suspect not.

[Mackofthejungle]

People scream about hybrids being overly complicated and heavy.. but honestly, they could be built so simply. I love the range extender concept, it's so beautifully simple.

Electric motor and battery in the back, and small 2 or 3 cylinder engine in front with no drivetrain hookup required and far simpler cooling. Small battery pack, easily upgraded or replaced. Small engine, easily serviced and replaced. Could be fitted to any modern car... If my Fiesta range dropped to 250 miles from 400, but I got electric power with a range extender.. Maybe 50 miles of plug in only.. It wouldn't affect my day to day at all, and I could be pootling about on battery power. I don't understand why this reality never happened!!

Too late now though, everything has to be pure battery, which is just a pain if you want that occasional freedom and aren't rich.

Good on Mazda for their continuing engine madness though. Nice to have something a little different.

[vaud]

hiccy18 said:

Interesting, but the i3 REX was limited by small fuel range meaning you could do better with a bigger battery and no REX. I hope Mazda create a car that can handle long journeys in an effective manner, but I suspect not.

One source: "Now, Mazda is repurposing the rotary engine as a way to extend its range, starting with the MX-30. The current MX-30 has an unimpressive range of between 100 to 124 miles. Mazda is expecting to increase the range to up to 248 miles for the upcoming MX-30 thanks to the addition of a rotary battery extender."

[pquinn]

Not exactly a new idea, the Audi A1 e-tron concept proposed using the same design back in 2010.

[hiccy18]

vaud said:

hiccy18 said:

Interesting, but the i3 REX was limited by small fuel range meaning you could do better with a bigger battery and no REX. I hope Mazda create a car that can handle long journeys in an effective manner, but I suspect not.

One source: "Now, Mazda is repurposing the rotary engine as a way to extend its range, starting with the MX-30. The current MX-30 has an unimpressive range of between 100 to 124 miles. Mazda is expecting to increase the range to up to 248 miles for the upcoming MX-30 thanks to the addition of a rotary battery extender."

I guess someone might like that, but to me it sounds like worst of both worlds; what's the advantages of the REX over another 20kwh of batteries?

[BrettMRC]

Johnny G Pipe said:

Yep, so this is just like an i3 then, but with ditchwater-spec design and with a REx that will use oil and wear its tips out.

Progress!

Show us on the doll where Mazda touched you?

[Andy665]

Isnt the e-power drivetrain in the Qashqai a range extender?

[samoht]

hiccy18 said:

I guess someone might like that, but to me it sounds like worst of both worlds; what's the advantages of the REX over another 20kwh of batteries?

The advantage is if you can't find anywhere to charge the batteries on a long journey, you can always find a petrol station every 150 miles, so your trip won't be significantly affected by chargers being broken, busy or non-existent.

Eg https://twitter.com/trent_dan/status/1612386653670...

A range-extender like this is an automotive omnivore, which can effectively exploit the best available source of energy in any situation, be that petrol or electricity, to keep mobile.

Andy665 said:

Isnt the e-power drivetrain in the Qashqai a range extender?

Kinda, but the difference is that it only has a small battery that's not worth plugging in. So the engine runs most of the time, it just drives a generator which powers the electric motors that drive the wheels. So similar drivetrain layout but with a much smaller battery. Think diesel-electric locomotive.

[Krikkit]

otolith said:

As a simple, compact, lightweight range extender with excellent NVH characteristics, it has appeal. Unlikely to be very fuel efficient, but probably doesn't matter for this application. Not going to make the car in any way more interesting to drive, though.

Rotaries can be very efficient when kept in the right point of the BSFC map and not varying RPM, you can also gain efficiency by removing pumping losses from not needing a traditional throttle etc too.

Be interesting to see what they quote compared to other Rex.

[hiccy18]

samoht said:

hiccy18 said:

I guess someone might like that, but to me it sounds like worst of both worlds; what's the advantages of the REX over another 20kwh of batteries?

The advantage is if you can't find anywhere to charge the batteries on a long journey, you can always find a petrol station every 150 miles, so your trip won't be significantly affected by chargers being broken, busy or non-existent.

Eg https://twitter.com/trent_dan/status/1612386653670...

A range-extender like this is an automotive omnivore, which can effectively exploit the best available source of energy in any situation, be that petrol or electricity, to keep mobile.

Andy665 said:

Isnt the e-power drivetrain in the Qashqai a range extender?

Kinda, but the difference is that it only has a small battery that's not worth plugging in. So the engine runs most of the time, it just drives a generator which powers the electric motors that drive the wheels. So similar drivetrain layout but with a much smaller battery. Think diesel-electric locomotive.

BMW have already tried that, the market decided there was a better solution; I suspect this will go the same way.

[Evanivitch]

Great idea as a PHEV owner, with effectively a Corsa engine in my car.

But it's 10 years too late and the MX-30 has not proven itself as a good EV platform, unlike the Korean EV/PHEV/Hybrid platforms. It's hard to believe they'll do well with this.

[Evanivitch]

Scott-R said:

As the owner of an i3 with range extender, I’m always amazed that more car companies didn’t follow suit. Even my 7 year old i3 has 100 miles of electric range, and I get another 80ish when running the Rex. Even today I don’t think there’s a PHEV that can match that.

Charge it when you can, put petrol in it when you can’t. It’s not perfect but it works

Ampera has a different balance. 30-40 miles electric and then 300 miles on petrol REx/Generator (only rarely does the ICE directly drive the wheels)

[Limpet]

hiccy18 said:

vaud said:

hiccy18 said:

Interesting, but the i3 REX was limited by small fuel range meaning you could do better with a bigger battery and no REX. I hope Mazda create a car that can handle long journeys in an effective manner, but I suspect not.

One source: "Now, Mazda is repurposing the rotary engine as a way to extend its range, starting with the MX-30. The current MX-30 has an unimpressive range of between 100 to 124 miles. Mazda is expecting to increase the range to up to 248 miles for the upcoming MX-30 thanks to the addition of a rotary battery extender."

I guess someone might like that, but to me it sounds like worst of both worlds; what's the advantages of the REX over another 20kwh of batteries?

In most cases it's significantly easier, quicker and more convenient to fill up with petrol en-route than it is to plug a car in and charge it.

[BigChiefmuffinAgain]

hiccy18 said:

Interesting, but the i3 REX was limited by small fuel range meaning you could do better with a bigger battery and no REX. I hope Mazda create a car that can handle long journeys in an effective manner, but I suspect not.

I thought the I3 range extender was plagued by problems which is why BMW quietly dropped it ? Something to do with the actual petrol engine not being used that much by owners ? Or maybe it's my memory that is plagued by problems....

[budgie smuggler]

These seem like a good idea as a stop gap while battery tech/charging networks mature. Local journeys with the battery, and the rex for occasional long trips.

I presume that means it can be lighter than something with the same range achieved by battery alone? The main thing for me though would be that it allows for quick refueling rather than 20 minute+ queues for chargers, finding out the chargers are hogged by somebody etc.