I too sense myself going through this auto pilot and it’s remarkable.
It's just habituation. You can "sense your autopilot" at anytime by purposefully and intentionally bringing your attention to whatever it is you're doing automatically.
Have you ever been listening to music while doing something else and eventually the music becomes background noise you forget is even there? That's habituation. Have you also suddenly been aware of it again if a new song comes on the radio or the announcer comes on or it changes in some way? In that case, it's your subconscious automatically bringing your consciousness back to it to alert you to the change. (As it's been monitoring the music even as you haven't been aware of it.) However, it's still possible to intentionally bring your attention back to something that's been habituated.
Was scary but at the same time remarkable because my subconscious guided me, stopped and accelerated without me having to think about it.
Do you even walk or type? :) Think about it.