It’s widely expected that the upcoming next-generation Mazda3 will make its first public appearance late next month at the Los Angeles Auto Show. The highly anticipated model will sit on the newest SKYACTIV architecture developed by Mazda, and it will also house an engine that promises to get a lot of people talking.
That would be the SKYACTIV-X, and, according to Mazda, it will deliver the fuel economy of a diesel engine but the “clean” properties of a gasoline engine. This is thanks to a new approach called SPCCI, for Spark-Controlled Combustion Ignition. In short, this is a powertrain with a revolutionary method of combustion.
Here’s how Mazda explains the new technology:
“In a gasoline engine, the fuel-air mixture is ignited by a spark from the spark plug. In a diesel engine, the fuel-air mix is compressed and ignites through pressure and heat alone. Diesel is more energy dense than gasoline, which also means more air and less fuel goes in, making for better fuel economy. And although diesel engines tend to release less carbon dioxide than gasoline engines, they emit particulates that, unless trapped or treated, can cause pollution. Diesels, which are often turbocharged, have a reputation for having lots of torque even at low revs, while gasoline engines can rev higher and produce more horsepower at those high revs.”
And it adds this:
“SKYACTIV-X offers the best of both diesel and gasoline engines with none of the disadvantages. It does this thanks to a new technology called Spark Controlled Compression Ignition (SPCCI). Running on regular gasoline, SPCCI works by compressing the fuel-air mix at a much higher compression ratio, with a very lean mix. The SKYACTIV-X engine uses a spark to ignite only a small, dense amount of the fuel-air mix in the cylinder. This raises the temperature and pressure so that the remaining fuel-air mix ignites under pressure (like a diesel), burning faster and more completely than in conventional engines.”
Boil down the technical jargon, and what you get are the benefits of a diesel engine’s fuel economy, without the format’s drawbacks, in the same way that a turbocharger provides the power of a bigger-cylinder engine without the heftier fuel consumption the latter usually inflicts.
American colleagues testing out models equipped with the SKYACTIV-X technology obtained combined fuel consumption figures of 40 mpg (or around 5.9L/100 km).
We’ll be learning a lot more about the Mazda3 and its powertrain if/when it debuts in Los Angeles, and especially when we get to climb behind the wheel when it officially hits the market.