The warning light on the dial turns on (on certain versions together with the message on the display) when the car exceeds the speed limit set previously (see “Reconfigurable multifunction display” in the “Dashboard and controls” section).
See also:
Steering Wheel Audio Controls
The remote sound system controls are located on the rear surface of the steering
wheel. Reach behind the wheel to access the switches.
Remote Sound System
Controls (Back View Of Steering Wheel)
...
Battery
The battery is of the “Limited maintenance” type: under normal conditions of
use the electrolyte does not need topping up with distilled water. ...
Low battery charge
Turning the key to MAR the warning light on the dial turns on, but it should
go out as soon as the engine is started (with the engine running at idle speed a
brief delay in going out is allowed) ...