Good food for thought, Ecky! It all makes sense to me. Do you suppose the messed-up exhaust pulses and still-present moving friction are why we don't see a lot more efficiency gains from cylinder deactivation? Most estimates I've read are in the single digit %.
(For others: I had speculated that 4-cylinder engines with rolling cylinder deactivation might replace 3-cylinders, but decided it was extraneous and edited it out of my original post just before Ecky replied. I need to stop obsessively editing posts and leave them be.
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