Mazda has announced a new four-cylinder engine, the Skyactiv-Z.

Set to replace the Skyactiv-G and Skyactiv-X engines, the Skyactiv-Z aims to build on Mazda’s commitment to high efficiency and low emissions while enhancing performance. Mazda snuck the news out in the company’s latest financial report, tucked up somewhere between revenue figures and operating costs.

The Skyactiv-Z will utilize “lambda 1 combustion,” a method designed to optimize the air-fuel mixture for greater thermal efficiency. Lambda=1 is just the technical term for stoichiometric combustion, it’s something almost all cars are programmed to aim for, however, Mazda, like Porsche, will be aiming for lambda to always remain at 1.00—during all phases of operation.

This is wild because in all combustion vehicles lambda will fluctuate—dropping to less than 1, known as a rich mixture, during warm-up phases and high power or high rpm demands. Meanwhile, a Lambda value greater than 1 is a lean mix and is most common when steady-state cruising on the highway.

Mazda says its super-lean burn technology promises cleaner emissions across a wide RPM range, aligning with stricter emissions regulations like Euro 7 in Europe and Tier 4 in the U.S. It’s unclear how Mazda will achieve its combustion goals, there may be a degree of hybridization with an integrated MGU along with an electric turbocharger, and potentially even some way of eliminating the accessory drive to reduce parasitic drag.

If Mazda goes the same route as Porsche we’ll likely see some alteration of ignition strategies as well, pulling timing during high boost events instead of richening the mixture. Naturally, this is all speculative.

The Skyactiv-Z engine will likely also incorporate many lessons learned from Mazda’s recent inline-six powerplants. By leveraging combustion technology developed for larger engines, Mazda hopes for improved environmental performance without compromising driving dynamics.

While Mazda hasn’t revealed full details yet, the Skyactiv-Z is slated to debut in 2027, with initial applications in Europe and the U.S. It’s part of Mazda’s strategy to streamline its engine lineup and focus on fewer, more efficient powertrains.

Mazda is also continuing to develop its rotary engine technology, with a focus on meeting modern emissions standards. This renewed effort follows a joint conference in May with Toyota and Subaru, where the brands affirmed their commitment to the future of combustion engines.