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Mazda begins mass production of MX-30 e-SKYACTIV R-EV PHEV with rotary engine genset

Mazda Motor has started mass production of the European model of the MAZDA MX-30 e-SKYACTIV R-EV at Ujina Plant No. 1 in Hiroshima City. (Earlier post.) This marks the use of Mazda’s first mass-production rotary engine vehicle in 11 years since the Mazda RX-8 was discontinued in June 2012. Mazda has cumulatively produced over 1.99 million rotary engine vehicles.

The MX-30 e-SKYACTIVE R-EV is a plug-in hybrid model offering an 85km battery electric driving range, with the rotary engine genset delivering additional power to extend the driving distance. The entire driving range is motor-powered.



The newly developed 830 cm3 rotary engine is packaged alongside the generator and a 125 kW (170 PS) motor in the engine bay. The single-rotor engine delivers a maximum output of 55 kW (74 PS) at 4,700 rpm, and is more compact than a reciprocating engine with similar output.


e-SKYACTIV R-EV electric drive unit

Introduced in 2020, the MX-30 is Mazda’s first mass-production battery electric vehicle, adding both a mild hybrid model and new plug-in hybrid model to Mazda’s product lineup.

Environmentally-conscious materials were intentionally adopted in the design process, applying cork and fabrics made from recycled materials in ways that bring out their natural appeal and create a comfortable interior. Mazda keeps striving to reduce its environmental footprint throughout the production process.


Albert E Short

This is the first pure serial PHEV (the ICE never directly drives the wheels) that I have seen mass produced. My one complaint about my Clarity is that the sound of the generator recharging the battery is harsh, but I presume this rotary Mazda goes hmmmmmmmm.


It seems like a PHEV version of Nissan e-power (with a rotary engine).
I wonder why Nissan don't make a PHEV version - I am sure they have simulated it and have a good reason....
(Or maybe that's what they want us to think .....)
+ I wonder how efficient that rotary engine is.
Anyone know?


Rotary engines don't have to be inefficient all the way back in the 1980s NASA did a funded study for rotary engines in aircraft to replace turboprop and leaded fuels. Those stratified charge engines beat diesels on a grams per kWh / BSFC. The key points are you absolutely must use direct injection and you also must not mix oil with the fuel.

These Mazda engines are direct injection and they also have 2.5mm apex seals plus side wall oil ports that keep the oil out of the airflow. Those oil ports were patented also in the 1980s they extend the life of the apex seals 5 times vs gas/oil mixing. With larger 2.5mm seals these engines will see well over 20,000 hours of use on a larger 2.5mm sized seal. The total usable height of a apex seal is contingent on its width the ratio is fixed due to harmonic bending and coupling to the springs holding the seal to the wear face. Wider seals allow taller seals which gives more wear surface length and also a wider wear surface for more surface area. Typical 2mm apex seal wear rates are in the 0.007" per 100 hour of full power use. With direct oil port side wall lube those rates drop by 5x and with 2.5mm seals with 125% the surface are the should be at least 25% less.

I have raced RX7s off and on for decades my first car was a Gen1 RX7 and I have owned all three gens over the years. I have rebuilt over half a dozen rotarys by my own hands they are a passion of mine. Apex seal wear is the limiting factor for any rotary motor the side and corner seals are bathed in oil from the oil cooling of the rotor most last two or three rebuilds. Mazda is also using plasma coatings on the wear surface these can be very strong think tungsten carbides or polycarbonate diamond I would expect those coatings to last well past 20,000 hours of full power use.

Mazda is using a system similar to this patent
United States Patent 3814555

NASA direct injection data.


Thanks, James.
OK, so 20,000 hours of operation should be OK for a Genset in a PHEV.
That should give you 25 years at 2 hours per day of genset use - which should be enough.
Also, they should be able to tune the use of the engine to maximise efficiency and minimise wear.


20,000 hours could be more than 500,000 miles considering PHEV can run around town on batteries


@SJC, sure - there should be no problems with rotor tip wear.
And if it is a nice small engine, so much the better.


Given that a EV uses about 250_350 watt hours per mile. The run time on the generator will be done at peak efficiency which for most ICE engines is centered around 75% of peak power. The BSFC minimum point is a bullseye around that 75% of maximum output point. This engine was designed for 54kw so 75% of that is 40kw running the engine at its peak BSFC eff. point. Taking an avg 300 watt hours per mile that implies 16kWh of usable charge in the battery for an 85km(53mile) range. 40kw of output charges 16 kWh in 24 minutes or 4/10 of an hour call it 30 min to account for charging losses. Put another way one hour of charging yields 106 miles of range.

The frame will rot out well before the engine fails due to apex seal wear. Even older rotary engines using direct injection oil into the intake ports could go 5000 hours before the seals let go. That's well over 500,000 miles if used only as a series hybrid charging the pack probably from 20% DOD to 80% where that range is equal to 16kWh. Given how cheap apex seals are and rebuilding a rotary is easy process only three moving parts and a set of seals.

The more logical way to use the engine is to allow it to load follow while at continuous speeds a vehicle uses around 25kw to move at motorway speeds that is less than 50% of the peak output apex seal wear is directly proportional to rpm and engine load in BMEP. Lowering either cuts the wear rates in kind. Half the rpm and load more than doubles the lifetime. engines have a broad area around the BSFC peak that is still near peak efficiency and stratified charge engines excel in this area they run throttleless and lean with or without high levels of EGR. Running this engine at 2500 or less rpm and 25kw would probably still return great mileage numbers.

The fact that they chose 4700rpm as the peak when rotary engines can and do rev to 9000+ rpm shows they purposely down graded its peak horsepower rating using a more normal test point of 6500rpm this rotary should be making well over 100hp per liter of sweep area. 13B carbonated engines routinely returned 130+ hp per liter and turbo gen 3 rotary could be boosted into the 200+ range per liter Mazda designed this generator for the long haul.


I forgot to point out why you would want to load follow at high continuous speeds vs a saw tooth charge discharge pattern at peak efficiency. Batteries are much MUCH more expensive than apex seals and any rebuild costs. Lithium ion batteries have a limited charge discharge cycle life 1000 to 3000 cycles to 80% DOD is typical. It makes more sense to keep the number of cycles down while cruising at motorway or exurban speeds. To cover 850km got a uncommon distance in the States in a single day. I personally do 900+ every two or three weeks each way. That's ten charge discharge cycles if you have a 85km range in the pack. The other choice is to use the pack at each end of the journey when in the urban areas and then run the engine in load following mode keeping the pack at 80% full until you get to the stop and go urban portion of the trip. Load following in the motorway would be in tbe 20 to 50kw range right near the heart of peak BSFC.

For people like myself who make regular long distance trips and also go off grid at the end of those trips for days at a time having a 50+kw generator on site makes for a perfect match. Can run computers ,test equipment and most importantly climate control in a 24/7 basis with extra fuel in jerry cans or 55 gal drums in a trailer towed behind this kind of SUV is a compelling case.

Roger Pham

Agree with James that PHEV is the way to go, due to many advantages over the pure BEV. The most important advantage is independence from the electricity grid. With extreme summer and winter temperatures in many cities, power outages are common and the grid simply cannot cope with such a surge in demand. During these times, the PHEVs do not have to draw from the grid, but instead can contribute to the grid, making it more stable and resilient.

The engine should be clutched to the drive axle during hybrid mode to transfer mechanical motion directly to reduce wear and tear on the electric power train, as well as reducing the size of the e-motor and inverter. Furthermore, when the engine is clutched directly to the drive axle, the generator now can also act as an additional e-motor, thus when combined with the engine's power, can nearly DOUBLE the 125-kW power of the dedicated e-motor. So we have the additional power of a 55-kW engine plus 55-kW generator in addition to the 125-kW e-motor. Total power would be 235 kW, which would make it an exciting vehicle that can compete with pure BEVs.
The main e-motor can be mounted on the rear axle, while the engine and generator on the front axle, thus providing 4-wheel drive just like in higher-level BEVs, without any complicated transmission.

Please note that the engine does not have to load follow. This is possible because both the generator and e-motor can add more torque during acceleration and uphill climb, and can recharge the battery during deceleration and downhill descent while the engine can maintain its peak-efficiency mode.

I think that PHEVs with light-weight and compact engine to make up for the bulk of the battery pack in order to have comparable weight and internal space to comparable ICEVs is much more desirable than a pure BEV that is heavier and hard on tires and consume too much battery resources. The grid-independency capability is price-less!...A must-have at any price...but fortunately, PHEVs are usually priced LOWER than comparable pure BEVs.

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