take out the this part of the condition. Also, a vehicle may not be able to move but still be alive. Best to use the canmove condition for trucks.
example-
! canmove truck1 && ! canmove truck2 && ! canmove truck3
If they're all tanks, lets say Russian tanks, your trigger could work like this-
East, Present, with condition-
(("tank" counttype thislist) == 0)
Remember, the trigger radius has to be large enough to cover the route of the tank convoy.