Mazda's 'Skyactiv-3' Engine Could Be As Clean As Some Electrics With 56% Thermal Efficiency

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Mazda has been vocal about its plan to continue developing internal combustion engines despite a major industry push towards electification and EVs. The company displayed its innovative Skyactiv-X engine last year, and now Automotive News reports that a next generation motor—called Skactiv 3—will offer efficiency levels that could yield overall CO2 output similar to that of some EVs.


With Mazda’s Skyactiv-G engine having been out for a while now, and Skyactiv-X coming soon—that’s the one with the innovative Spark Controlled Compression Ignition technology—the company is apparently working to further increase internal combustion engine efficiency with a new generation of Skyactiv called “Skyactiv-3.”

Automotive News reveals what Mazda’s powertrain chief said at a technical conference in Tokyo:

After [Skyactiv-X], the automaker will prioritize boosting the thermal efficiency of its engines, said Mitsuo Hitomi, Mazda’s managing executive officer in charge of powertrain. Doing so reduces the amount of combustion energy lost to heat while increasing the amount harnessed to power the wheels.


The story goes on, saying:

If Mazda can increase the thermal efficiency of its third-generation Skyactiv engine by about 27 percent, to 56 percent, it can achieve emissions on a par with an EV, Hitomi said.


Yes, 56 percent thermal efficiency is impressive.

For comparison, Toyota’s new 2.5-liter “Dynamic Force” engine allegedly has a thermal efficiency of 40 percent in gas vehicles and 41 percent in hybrids. And based on the quote above, the upcoming Skyactiv-X engine seems to have a thermal efficiency of about 44 percent. So going up to 56 sounds like a major leap.


Ultimately, that efficiency number would bring a gas-powered vehicle’s total CO2 output on par with that of an EV that gets its power from a natural gas powerplant, as the car news site writes:

Mazda believes it can cut carbon dioxide emissions by 25 percent. That would give Mazda’s gasoline engines real world well-to-wheel fuel economy comparable to EVs deriving their electricity through the burning of liquefied natural gas, Hitomi said.


Last year, Mazda’s head of powertrain development told Australian car website caradvice that electric vehicle manufacturers were “controlling the minds of the media” to make them think EVs produce no CO2. But while electric vehicles might not produce local emissions, their batteries tend to ultimately receive charge from natural gas or coal power plants, which do produce emissions. Do this wrong and you switch from gas-powered cars to coal-powered cars.

As Mazda mentioned in its Global Tech Forum in Frankfurt last year, comparing EVs and internal combustion engines requires a “Well-To-Wheel” analysis, which can be broken down into “well-to-pump” and a “pump-to-wheel” studies. The former looks at energy needed to extract raw materials, refine them or generate electricity from them, and transport the resulting fuel. The latter considers inefficiencies in the vehicle such as those in the engine and drivetrain. You can read more about such a study in our post here.


Automotive News says the automaker doesn’t have a timeline for this third generation of Skyactiv gas engines, but in the company’s Global Tech Forum presentation from last year, it didn’t mentioning any new generation of Skactiv in the “2021 and beyond” column, so this seems like it may be quite a long-term vision:


There’s also no mention in the story of how Mazda plans to achieve its 56 percent efficiency figure, or whether electrification will be involved. So right now, this is all just talk.

But then again, Mazda’s Spark Controlled Compression Ignition Engine was also all talk until they actually built a few and let journalists drive them last year. So we’ll just have to wait and see.