Folding back the rear seat backrest
WARNING Risk of becoming trapped when adjusting the seats
When you adjust a seat, you may trap yourself or a vehicle occupant.
When adjusting a seat, make sure that no one has any body parts in the sweep of the seat.
WARNING Risk of injury if the rear bench seat/rear seat and seat backrest are not engaged
If the rear bench seat/rear seat and seat backrest are not engaged they could fold forwards, e.g. when braking suddenly or in the event of an accident.
If this is the case, the vehicle occupant would be forced into the seat belt by the rear bench seat/rear seat or by the seat backrest. The seat belt cannot protect as intended and could result in additional injury.
Objects or loads in the boot/load compartment cannot be restrained by the seat backrest.
Make sure that the seat backrest and the rear bench seat/rear seat are engaged before every trip.
NOTE Damage caused by trapping the seat belt when the seat backrest is folded back
The seat belt could become trapped and thus damaged when the seat backrest is folded back.
Ensure that the seat belt tongue has been inserted at the side in the marked position.
NOTE Damage to the roof lining when the rear seat backrests are folded forwards and backwards
The roof lining can be damaged when the rear seat backrests are folded forwards and backwards.
Before folding the rear seat backrests forwards and backwards, insert the head restraints.
Folding back the rear seat mechanically
Move the driver's or front passenger seat forwards, if necessary.
Swivel rear seat backrest 
back until it engages.
back until it engages. Make sure that the red marking of the lock verification indicator is no longer visible. Otherwise, the rear seat backrest will not be locked.