Low speed automatic cancellation

ACC is not functional at vehicle speeds below 16 mph (26 km/h). Once the vehicle speed drops below 16 mph (26 km/h), an audible alarm will sound and the automatic braking will be released.
See also:
Resuming a set speed
Press and release RESUME. This will automatically return the vehicle to
the previously set speed. ...
Adjusting the front power seat
WARNING: Never adjust the driver’s seat or seatback when the
vehicle is moving.
WARNING: Do not pile cargo higher than the seatbacks to
reduce the risk of injury in a collision or sudden stop.
W ...
Split-folding rear seatbacks
One or both rear seatbacks can be folded down to provide additional
cargo space.
To lower the seatback(s), pull the
release handle(s) located inside the
trunk.
Fold the seatback(s) down.
...
