Mazda Patents Six-Stroke Engine That Uses Gasoline and Traps Carbon

Mazda has filed a patent for a six-stroke engine that could change how gas-powered cars handle emissions. The idea: pull hydrogen from ordinary gasoline, burn that hydrogen for power, and capture the carbon before it reaches the tailpipe. If it works as described, drivers could keep using gas stations while producing almost no CO2 from the exhaust.

S. Patent and Trademark Office. It is not a hybrid or fuel-cell system, and it is still only a patent, no working vehicle has been built. Mazda has a history of taking on unconventional engine projects, including the rotary engine and its SKYACTIV-X gasoline compression-ignition technology, so this approach fits the brand's reputation.

The engine builds on the usual four-stroke cycle but adds two more steps. During what would normally be the exhaust stroke, the hot exhaust is sent through a decomposer. A fuel injector adds gasoline to the hot air, and carbon sticks to a catalyst inside the reformer. The hydrogen is routed to a small storage tank, while the captured carbon goes into a separate recovery unit.

The engine can also run on gasoline temporarily when not enough hydrogen is ready, meaning some CO2 would be released during those moments.

The potential benefits are significant: cleaner tailpipe emissions, less smog, and less CO2 entering the atmosphere. It would also keep the existing fuel infrastructure relevant instead of pushing all vehicles onto the electric grid. But there are real drawbacks. The six-stroke engine is more complex than a standard gas engine, which likely means higher maintenance and repair costs.

5 pounds of carbon, so a 15-gallon tank could produce more than 82 pounds. That carbon tank would need to be emptied regularly, possibly at service visits or future carbon-emptying stations.

Efficiency, power output, cost, and practicality are still unknown. Mazda's SUV lineup could be a possible testing ground, especially for urban driving, but the engine may never leave the patent stage. Automakers regularly file patents for ideas that never make it to production.

This one offers an intriguing path for gas engines to coexist with EVs, but it still has to prove itself as a viable, affordable, and reliable technology.