Mazda’s Rotary Engine Might Get New Life As Toyota Range Extender


Toyota shouldn’t have much trouble fitting a tiny rotary engine into the boxy E-Palette.

Pure Electric Version of Mazda 2 – This One Lacks the Range Extender

When trial testing begins in a few years, Toyota’s versatile E-Palette could potentially have a tiny rotary engine on board as a range extender for the model’s electric powertrain. The combustion mill would boost the boxy model’s range, so that the machine wouldn’t sit at charging point out out of commission for such a long time.

In its announcement for the E-Palette, Toyota listed Mazda as one of its initial partners on the project, which also included Amazon, DiDi, Pizza Hut, and Uber.

“Mazda will provide technical information on a [rotary engine] range extender to be used in the vehicle being developed. We will reveal more details at an appropriate time,” Mazda spokesperson Jacob Brown told Green Car Reports.

Mazda has been working on a rotary range extender for several years, including putting one in the Mazda2 plug-in hybrid concept. In 2017, the company filed a patent for a Wankel stop-start system that specifically referenced the engine’s role as a range extender, too. Rumors have also pointed to Mazda using this powerplant in its own vehicle, in addition to the Toyota partnership

The rotary engine’s high power output relative to its small size make it a good fit for packaging as a range extender. The poor fuel economy is less of an issue, too, because the electric powertrain functions as the primary means of moving the vehicle.


Toyota unveiled the E-Palette concept at CES. The company imagines it more as an open platform than a traditional vehicle. Companies would sign up to use the model and would be relatively free to modify it, including adjusting the interior and fitting different autonomous systems. The partners would also have access to Toyota’s big data center for tasks like monitoring the state of the vehicles on the road.

Source: Green Car Reports

Categories: Mazda, Toyota


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21 Comments on "Mazda’s Rotary Engine Might Get New Life As Toyota Range Extender"

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The Wankel rotary engine design should be able to improve its economy in and EV generator role by optimizing operating rpm. It does not have to generate good torque over a wide range of rpm speeds as in conventional operation, but can be tuned to work best at one speed for generating electricity.


mehh.. crap!!!

Nah, I agree with him. A regular tiny 3 cylinder makes a much better range extender than a rotary. Lets see the numbers and if this ever comes to be.

Or a modified two cylinder motorcycle engine, such as the one installed in the BMW i3 REx. Derived from the smallest motorcycle engine used by BMW motorcycles.





What happened to the free-piston linear generator range extender idea? Haven’t heard anything about it for years.




The challenge will always be to make the Wankel engine clean enough. Those of us who are now convince that EVs are the right route for sustainable transportation would ask how much additional range the vehicle could have if extra batteries were added to replace the engine, generator, radiator, fuel tank, exhaust system, catalytic converters and more the come with this range-extender concept.

This question will increasingly be answered in favour of the battery: falling prices, growing range, increasing charging speeds, expanding charging networks.

PHEV’s are dead by 2020.

I’m with Hart, though the Wankel would make a good series hybrid range extender I have to wonder how necessary it is at this point with 2-300 mile EVs and 120kw charging available, why haul it around if you really don’t need it?

The buyer is going to answer that question eventually. Moore’s Law is in effect on BEVs. When that purchase price (not TCO) differential is hit and people are still buying gassers, it should be clear to everyone that their motivations are fear or political rejection. I feel like this will largely be a N. American problem only.

– in very cold weather, especially combined with driving in snow, AER drops significantly.
– In cold weather, with a cold battery charging speed is significantly reduced.
– gasoline refueling is plentiful and quick
– having a gasoline engine background increases tolerance for outages

We shouldn’t pretend that there aren’t obvious benefits to having an ICE there. ICE drivetrains are relatively cheap, and serial hybridization lowers the cost of the ICE-based part and makes packaging easier. At volume I would expect EREV to be comparable in cost to a long-range BEV, at least until battery costs get down to the $100/kWh.

Agreed on the waste of adding all the ICE support systems. And by the time they get it up and running (w/ required reliability) batteries will have gotten even cheaper/more dense.

The future cost and density of batteries are unknowns.

What if we can make cheap batteries, but have to sacrifice some density and charging capability to make them durable enough for use in cars?

Maybe 4-5 years ago this would have been useful… But if it’s only announced now, it’ll be 2-3 years for commercial deployment… Free-piston engines or standard Atkinson-cycle probably makes more sense.

Given that in a serial hybrid a range extender wouldn’t be used much, the high power to weight ratio and compact size of rotary engines are a good fit.

Infrequent use would also mean that fuel economy and durability would be less important, but since in a serial hybrid the engine can run at a constant RPM for peak efficiency, the fuel economy and durability issues would be further diminished.

You do know that most of the weight is that other stuff – radiator, exhaust, catylitic converter, etc. Nissan has a 1.5L 3 cyclinder that weighs only 88 lbs. That small size goes with low efficiency from every mazda we have seen. A tiny 1L achieves 37% peak efficiency, lets see if this thing even can break 33%, let alone the 41% toyota is getting in its new engines.

Two of these would give even better space optimisation and better efficiency:

This looks like like the perfect fit. Thanks for the link! Small and simple. and given that it also runs on ethanol – which I hope the description “high fuel flexibility” implies – it would also be not too bad for enviroment… …not to get me wrong. When we can offer BEV with sufficient range for all use cases that will be great. But meanwhile EREV will help. That said, driving profiles of people span a wide range, and therefor we will quite likely never have a one-size-fits-all solution. It would be helpful if people would analyze their (real) range needs and choose accordingly. I know oh so many people who never took their car for ANY travel further than 80 km… (germany, small country…) All of them would probably never need any range extender even with todays BEV ranges… (and they would carry unnecesarry weight around if they decided to buy an EREV or a long range BEV…) Not to mention that most of them have a second or third car… which could also serve as their ICE backup should they ever decide to travel further without using a train or a plane… There is so much development going… Read more »