Authority Sentries are one of the side activities in RAGE 2. They are large objects found in every region. When you get closer to them, you will be warned with a purple light. If you don't leave fast enough, you will get shot. This can lead to your death or destruction of your vehicle.
What do I get from destroying Authority Sentries?
Destroy them to get money which you can spend on new items. You also get support points for one of your allies.
How to destroy Authority Sentries?
The best way to do that is to stay in your vehicle. The turrets mounted on your vehicle give you tremendous fire power. You can also move faster to avoid enemy fire.
The majority of the Authority Sentries have large objects located nearby (mountains, rocks, vehicle parts) - use them as a cover.