These locks are intended to help prevent children from accidentally opening the rear doors. Use them on both rear doors whenever a child rides in the rear seat of the vehicle.
If you slide the child safety lock to the lock position before closing that door, the door cannot be opened from the inside. The door can only be opened by pulling the outside handle.

Locking, Unlocking with Door- Lock Knob
Trunk LidMazda 6 Owners Manual: Manual transaxle removal/installation
1. Remove the battery, battery tray and battery bracket.
2. Remove the air cleaner compornent. (See INTAKE-AIR SYSTEM
REMOVAL/INSTALLATION.)
3. Remove the wheels, tires and splash shields.
4. Remove the under cover.
5. Remove the steering gear and power steering pipe. (See STEERING GEAR AND
...
Mazda 6 Owners Manual: Recommendations for Shifting
Upshifting
For normal acceleration and cruising, Mazda recommends these shift points:
*1 Always observe local speed limit regulations.
Downshifting
When you must slow down in heavy traffic or on a steep upgrade, downshift before
the engine starts to overwork. This gives better acceleration w ...