In the tC you could do this little song and dance to disable the beeping, it might work on the xD too.
- Set the LCD on the combination meter to the ODO display.
- Press and hold the TRIP meter reset knob for ten seconds or more within six seconds of turning the ignition switch to the ON position.
- Fastening the driver's seat belt while holding the knob cancels the buzzer reminder. When this occurs, the LCD displays 'b-OFF'.
When in this mode, the buzzer reminder can be switched between ON and OFF each time the TRIP meter reset knob is pressed. The LCD displays 'b-ON' or 'b-OFF' according to the buzzer reminder ON/OFF status. The display changes to the ODO or TRIP meter if the knob is not pressed for ten seconds.
Performing the steps again when the buzzer reminder is off exits cancel mode. The cancel mode will also exit when the battery or combination meter connector is reconnected.