The direction the vehicle is moving is displayed while the vehicle is being driven.

Cruise Control Set Vehicle Speed Display (Some models)
Warning (Display Indication)Mazda 6 Owners Manual: Dynamometer
When inspecting and servicing the power train on the dynamometer or
speed meter tester, pay attention to the following:
- Place a fan, preferably a vehicle-speed proportional type, in front
of the vehicle.
- Make sure the vehicle is in a facility with an exhaust gas
ventilation ...
Mazda 6 Owners Manual: Drive belt auto tensioner inspection
1. Remove the drive belt. (See DRIVE BELT REPLACEMENT.)
2. Verify that the drive belt auto tensioner moves smoothly in the
operational direction.
Replace the drive belt auto tensioner if necessary.
3. Turn the drive belt auto tensioner pulley by hand and verify that it
rotates smoothly ...