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: Customer Assistance (Canada)
Satisfaction Review Process
Your complete and permanent satisfaction is of primary concern to Mazda. All
Authorized Mazda Dealers have both the knowledge and tools to keep your Mazda in
top condition. In our experience, any questions, problems, or complaints regarding
the operation of your Ma ...
Mazda 6 Owners Manual: No.4 air intake mode does not change
When performing an asterisked (*) troubleshooting inspection, shake the
wiring harness and connectors while performing the inspection to discover
whether poor contact points are the cause of any intermittent malfunctions.
If there is a problem, check to make sure connectors, terminal ...