In my Pontic campaign, I have a chariot with 3 silver chevrons. It is down to 17 men from 36 (? - not sure. it's been a while). 3 Uses:

1. It scares infantry. Line up behind your line and set to defend or it will charge without fail at the worst moment and disrupt your own line. The "frightened by chariots" is diplayed in enemy info boxes. This causes the enemy units to break sooner and fight less energetically.

2. It is good for bringing wavering units to a complete rout and final demise. Also for mopping up fleeing units.

3. Use as diversion. run to a flanking position and watch AI line up 1-2 units to face it. These will not be facing your main effort.