Must have something to do with the direct injection scheme. The linked article mentions it but does not explain it.
"A number of improvements to the Miata's combustion process were implemented, too. The shapes of the combustion chamber and piston feature a number of modifications to increase tumble flow speed, and thus, and knock resistance. A new high-pressure fuel injection strategy makes combustion more efficient, too.
There's some clever stuff going on with electronic controls here, too. At low RPMs, fuel is injected during the heat and pressure strokes, and just before the power stroke to create a richer mixture around the spark plug, creating more stable combustion. This was critical to give this engine a boost in low-RPM torque, but not at the expense of refinement and fuel economy."
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The Help for this program was created in Windows Help format, which depends on a feature that isn't included in this version of Windows.