From Panzer General 2 manual:
An example:UNIT CLASS AND EQUIPMENT TYPE SPECIAL
Tank Class: Overrun
Tank class units possess a special ability called Overrun; a powerful advantage usable under certain
conditions. A tank unit that conducts a devastating attack on a weakened foe has the possibility of
‘rolling over’ its opponent. If the tank’s attack eliminates the defender, an Overrun Attack message may
appear in the Information bar at the top of the Main Game screen. If this message occurs, the tank is
allowed to continue with its movement, and attack again. This represents a tank unit’s ability to smash
straight through weakened units. With luck, and a line of weak defenders, a tank may attack and
destroy two or three lesser units in a single turn.
The rest of your units have reduced an enemy infantry unit to 2 strength and an enemy anti-tank unit to 1 strength.
You move your 5 movement points Panzer 2 hexes to a position where it can attack both enemy units.
The Panzer attacks the 2 strength enemy infantry unit and overruns it (destroys the enemy unit).
The Overrun ability kicks in and your Panzer can now still move 3 hexes (or 2 if a similar recon staggered movement penalty is chosen) and shoot again.
You choose to attack the 1 strength enemy anti-tank unit and again overrun the enemy unit.
You still retain the possibility to move your Panzer.
Your Panzer expends the fuel of the movements and the ammo of the shots.