Well not necessarily. There are how many vehicle types in the mission? I.E. truck, jeep, jeep with mounted mg, hummer with tow, etc.
You only need to create a position for each vehicle type. All of the hummers should be based off of the same general model so just one position for hummers etc. It will require a little work because you have to find the position once for each vehicle "class" as we shall call it. But once you have that position, it will work on every vehicle you place.
How can I make it so it's aimed at the wheel of the car?
If you create it
inside the wheel, it instantly hits, and causes the effect. Just as if I created a bullet inside a soldier's head, he'll instantly die.