Manual cylinder deactivation?

[Angel And The Wolf]

Two engines. Both running during acceleration, and one de-clutched, and turned off, or idling, for cruising. The cruising engine could be a smaller 3 cylinder.
Of course, if you are sticking to the engine you have, none of this will work.
In that case, permanently deactivate every other cylinder in your firing order, and install an electric supercharger for accelerating, cutting it off, or down, for cruising.

[cRiPpLe_rOoStEr]

Originally Posted by ProDigit

Roughly speaking for every 12% in gearing increase, you'll get a 10% of MPG increase.
It's not linear, meaning you'll get better MPGs at lower speeds, and MPGs at highway speeds will be closer to identical; to worse (when the engine load is too high, and the engine is pinging or knocking).

That's a good point. But anyway, as I previously said, I'd never hold my breath for just a taller gearing to fare exactly the same way as cylinder deactivation, even though in most cases I'd not expect it to actually harm fuel-efficiency.