[oynqr]

Isn't cylinder deactivation for when you are at constant speed at low throttle?

[landgenoot]

They open the exhaust valves of every cylinder while coasting.

Therefore, the engine keeps running, but there is no combustion.

You can see your live fuel consumption go to 0 when you lift the gas pedal on a modern ICE car.

[kjkjadksj]

That is whats always happened when you lift your pedal on a manual car at least.