While driving across the wasteland, it is not uncommon to run across a bandit watchtower:
These are not terribly dangerous while driving (their machine gun doesn't do an awful lot of damage, and they don't chase you, obviously) and there are certainly quite a few ways to get rid of them (ramming them, or stepping out of your vehicle and using a sniper rifle on the operator).
The thing is, I've never managed to get a lock on them to properly take them down with vehicle mounted weapons. Firing blindly at them will work, but some are placed in such a way as to make that nearly impossible. Is there some way to do this that I am missing, or is it impossible to get a lock on them?