The new range of Mazda's large cars will get an inline-six engine in either petrol or diesel. They'll be longitudinally mounted, and hybrid augmented.
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Mazda is committed to bringing back the six, with an investor report revealing the brand is working on a pair of longitudinally-oriented inline-six engines with 48V and plug-in hybrid technology.

In a presentation dubbed Fiscal Year 2019 March Results there's a graphic dedicated to future product and, under the "Large Architecture" header, features straight-six Skyactiv-X and Skyactiv-D engines.

The presentation also confirms the engines will be longitudinally-mounted, available with all-wheel drive, and backed by either 48V or plug-in hybrid augmentation. The slides were initially reported on Jalopnik, which received the following response from a Mazda spokesperson when asked about the slides:

“We’re excited to bring these powertrains to our future vehicles as we continue on our path to premium. We know our fans will be yearning for additional details, however specific models, performance figures and market rollout will be disclosed at an appropriate time.”

This is the first mention of a modern Mazda engine bigger than a four-cylinder. The company has instead focused on its Skyactiv-X engine, a 2.0-litre four-cylinder reliant on a process called Spark Controlled Compression Ignition (SCCI).

Unlike normal petrol engines, which rely on spark plugs to ignite the air-fuel mixture, the new engines are also able to operate like a compression-ignition engine. In other words, a diesel.

The process allows Mazda to run with a leaner air-fuel mix and minimises lost heat energy, an evolution of the ultra-high compression ratio it's using in the current Skyactiv range.

When conditions demand it the car will use spark ignition like a normal petrol engine, neatly avoiding one of the issues that's held other manufacturers back when trying to develop a compression-ignited petrol engine – compression-ignition engines do their best work in a narrow temperature band.

It's interesting to see Mazda moving to bigger engines and a longitudinal architecture, but not unprecedented. It's an inherently smooth configuration, and the idea of a rear-drive Mazda 6 or similar with rear-drive and a straight-six is quite enticing.

Mercedes-Benz is using an inline-six in its latest range of AMG 53 models, while BMW has never really moved away from its straight-six roots. JLR also has returned to the I6 game of late.