I dunno. The gun is not aimed downwards, and i suspect the bullet drop is fairly limited for some distance, allowing for the cruiser to potentially pull in underneath the stream. Whoever is driving said cruiser will have some big metal balls to pull it off.

Checking Wikipedia it seems the round drops 1 meter pr 400 meters of travel.

https://en.m.wikipedia.org/wiki/GAU-8_Avenger#Accuracy