Leave it to a tiny car company like Mazda to pull off something the big players have been trying to figure out for years. That’s the deal with the new “SkyActiv-X” series of engines, which use revolutionary technology to achieve diesel-like fuel economy with gasoline. If you want to see how it likely works, Engineering Explained is here to help.

The trick to these new supercharged engines is all about compression. Mazda seems to have finally figured out homogeneous charge compression ignition—but only some of the time. The SkyActiv-X uses a form of compression ignition similar to a diesel at times, but it can also seamlessly change over to a regular spark ignition like any gasoline engine when needed. Mazda calls this Spark Controlled Compression Ignition. The result, the automaker claims, is 20 to 30 percent more powertrain efficiency than their conventional gas engines.


Jason from Engineering Explained breaks down how, if this works, you get the best of all worlds: tons of efficiency and tons of torque.

The major challenges, he says, are of course how to switch between spark and compression ignition. Mazda hasn’t yet stated how this works, but Jason theorizes they found a way to use the spark plug itself to control the timing of compression ignition—which is where the SPCCI name comes from.

And if you want to learn more about how homogeneous charge compression ignition engines work in general, he has this explainer too:

Why does this matter? Because as the automotive world seems poised to put all of its eggs in the electric car basket, Mazda is proving the gasoline internal combustion engine still has plenty of untapped potential. The future of energy and transportation should be a future full of choices, so this is an exciting moment for anyone who’s a fan of gas engines. Electrification is likely the future, but we won’t get there overnight, and it won’t mean much until our grid runs on renewable energy. Anything that makes ICE engines better in the meantime is a positive.


And it’s more cool shit from a company with a track record of cool shit. I’m excited to see where it goes.