If your vehicle rapidly closes in on the vehicle ahead because the vehicle applies the brakes suddenly while you are traveling in headway control, the warning sound activates and the brake warning is indicated in the display. Always verify the safety of the surrounding area and depress the brake pedal while keeping a safer distance from the vehicle ahead.
Additionally, always keep a safer distance from the vehicles behind you.

Mazda Radar Cruise Control (MRCC) Display Indication
Setting the SystemMazda 6 Owners Manual: Stopping The Smart Brake Support (SBS) System Operation
The Smart Brake Support (SBS) system can be temporarily deactivated.
When the Smart Brake Support (SBS) system is turned off, the Smart Brake Support
(SBS) OFF indicator light turns on.
When the engine is restarted, the system becomes operational.
NOTE
If the Smart Brake Support (SBS) system ...
Mazda 6 Owners Manual: Tires
For reasons of proper performance, safety, and better fuel economy, always maintain
recommended tire inflation pressures and stay within the recommended load limits
and weight distribution.
WARNING
Using Different Tire Types: Driving your vehicle with different types
of tires is dangerous. I ...