Manual says :

The speedometer receives wheel
speed data from the CAB via the CAN data bus and
can be verified by comparing the speed signal viewed
by the DRB IIIT from the wheel speed sensors and the
output seen on the Instrument Cluster.

CAB = Controller Antilock Brake

Sounds expensive $$$$

( but if it is effected by bouncing, could be a loose connection or maybe a loose wheel sensor ? )