He is patrolling, you say?
So a bunch of move wp and 1 Cycle wp.
After that cycle wp place a move wp on top of the car.
Now use a bolean like
blowncar when set to
true when the car is destroyed.
Now place a trigger, type
SWITCH and syncronise it with that Cycle wp.
in the condition of the trigger :
blowncarThat's all.
Also read about SWITCH triggers, they are very usefull
http://www.ofpec.com/editors/resource_view.php?id=475