The rear armrest in the center of the rear seatback can be used (no occupant in the center seat) or placed upright.

WARNING
Never put your hands and fingers around the moving parts of the seat and armrest:
Putting your hands and fingers around the moving parts of the seat and armrest is dangerous as they could get injured.
Split Folding
Head RestraintsMazda 6 Owners Manual: Driving on Uneven Road
Your vehicle's suspension and underbody can be damaged if driven on rough/uneven
roads or over speed bumps at excessive speeds. Use care and reduce speed when traveling
on rough/uneven roads or over speed bumps.
Use care not to damage the vehicle's underbody, bumpers or muffler(s) when driving ...
Mazda 6 Owners Manual: Sst
Some Ford SST or equivalent are used as SSTs necessary for
engine repair. Note that these SSTs are marked with Ford SST
numbers.
Note that a Ford SST number is written together with a
corresponding Mazda SST number as shown below.
Example (section ST)
Example (except section ST)
...