Ford Mustang Owner's Manual page 128

Seating and Safety Restraints
Press the button to rotate the head
restraint forward in order to
improve rear vision when there are
no rear seat occupants.
2nd row seat/split-folding rear seat (if equipped)
One or both rear seatbacks (coupe only) can be folded down to provide
additional cargo space.
To lower the seatback(s) from
inside the vehicle, be sure the head
restraint is in the upright position,
pull the strap to release the
seatback and then fold the seatback
down.
When raising the seatback(s), make sure you hear the seat latch into
place. Pull down on the seatback to ensure that it has latched.
WARNING: Before returning the seatback to its original
position, make sure that cargo or any objects are not trapped
behind the seatback. After returning the seatback to its original
position, pull on the seatback to ensure that it has fully latched. An
unlatched seat may become dangerous in the event of a sudden stop or
collision.
128
2012 05+ Mustang (197)
Owners Guide, 3rd Printing
USA (fus)