When driving after dark, the automatic dimming rearview mirror reduces the glare from headlights behind you, based in inputs from the mirror sensor. This feature is always active.
The auto dimming function cancels when the shift position is in R.
Honda Civic Owners Manual. Using the Smart Entry with Push Button Start System
When you carry the smart entry remote, you
can lock/unlock the doors, fuel fill door, and
open the trunk.
You can lock/unlock the doors and fuel fill
door within a radius of about 32 inches (80
cm) of the outside door handle. You can open
the trunk within about 32 inches (80 cm)
radius ...